Copolymeric stabilizing carrier fluid for nanoparticles

ABSTRACT

A composite particle that includes: a fluorescent semiconductor core/shell nanoparticle (preferably, nanocrystal); and a stabilizing additive of a (meth)acrylate copolymer having pendent phosphine, arsine or stibine groups.

BACKGROUND

Quantum Dot Enhancement Films (QDEF) are used as the light source forLCD displays. Red and green quantum dots are used in QDEF with a blueLED as the light source to give the full spectrum of colors. This hasthe advantage of improving the color gamut over the typical LCD displayand keeping the energy consumption low compared to LED displays.

Once the quantum dots are synthesized, they are often treated with anorganic ligand that binds to the exterior surface of the quantum dot.Colloidal quantum dot nanoparticles (preferably, nanocrystals) that arestabilized with organic ligands and/or additives can have improvedquantum yields due to passivating surface traps, controlling dispersionstability in carrier fluid (or solvent) or cured polymeric binder,stabilizing against aggregation and degradation, and influencing thekinetics of nanoparticle (preferably, nanocrystal) growth duringsynthesis. Therefore, optimizing the organic ligand and/or additive isimportant for achieving optimal quantum yield, processability, andfunctional lifetime in QDEF.

SUMMARY

Composite particles are provided that are capable of fluorescence andsuitable for use in quantum dot enhancement films.

In one aspect, the present disclosure provides a composite particle thatincludes: a fluorescent semiconductor core/shell nanoparticle(preferably, nanocrystal); and a stabilizing carrier fluid combined withthe core/shell nanoparticle, the stabilizing carrier fluid comprising a(meth)acrylate copolymer having pendent phosphine, arsine or stibinegroups. The stabilizing carrier fluid may serve as a carrier fluid forthe composite particles for further dispersal in a polymeric binder.

More particularly, the (meth)acrylate copolymer has pendent groups ofthe formula:

wherein each R¹ is a hydrocarbyl group including alkyl, aryl, alkaryland aralkyl;R² is a divalent hydrocarbyl group selected from alkylene, arylene,alkarylene and aralkylene;

Z is P, As or Sb;

Q is a functional group selected from —CO₂—, —CONR³—, —NH—CO—NR³—, and—NR³—, where R³ is H or C₁-C₄ alkyl, and subscript x is 0 or 1.

In some embodiments, one of the R¹ groups may be substituted for a groupof the formula —R⁶—Z(R¹)₂, to yield pendent groups of the formula:

where R⁶ is a divalent hydrocarbyl group selected from alkylene,arylene, alkarylene and aralkylene, and R¹, R², R³, Z and Q are aspreviously defined.

In one aspect, the present disclosure provides a composite particle thatincludes: a fluorescent semiconductor core/shell nanoparticle(preferably, nanocrystal); and a stabilizing carrier fluid comprising a(meth)acrylate copolymer having pendent phosphine, arsine or stibinegroups that is combined with, attached to, or associated with, thecore/shell nanoparticle. The fluorescent semiconductor core/shellnanoparticle includes: an InP core; an inner shell overcoating the core,wherein the inner shell includes zinc selenide and zinc sulfide; and anouter shell overcoating the inner shell, wherein the outer shellincludes zinc sulfide.

As used herein

“Alkyl” means a linear or branched, cyclic or acylic, saturatedmonovalent hydrocarbon.

“Alkylene” means a linear or branched unsaturated divalent hydrocarbon.

“Alkenyl” means a linear or branched unsaturated hydrocarbon.

“Aryl” means a monovalent aromatic, such as phenyl, naphthyl and thelike.

“Arylene” means a polyvalent, aromatic, such as phenylene, naphthalene,and the like.

“Aralkylene” means a group defined above with an aryl group attached tothe alkylene, e.g., benzyl, 1-naphthylethyl, and the like.

As used herein, “(hetero)hydrocarbyl” is inclusive of hydrocarbyl alkyland aryl groups, and heterohydrocarbyl heteroalkyl and heteroarylgroups, the later comprising one or more catenary (in-chain) heteroatomssuch as ether or amino groups. Heterohydrocarbyl may optionally containone or more catenary (in-chain) functional groups including ester,amide, urea, urethane, and carbonate functional groups. Unless otherwiseindicated, the non-polymeric (hetero)hydrocarbyl groups typicallycontain from 1 to 60 carbon atoms. Some examples of suchheterohydrocarbyls as used herein include, but are not limited to,methoxy, ethoxy, propoxy, 4-diphenylaminobutyl,2-(2′-phenoxyethoxy)ethyl, 3,6-dioxaheptyl, 3,6-dioxahexyl-6-phenyl, inaddition to those described for “alkyl”, “heteroalkyl”, and “aryl”supra.

The term “composite particle” as used herein refers to a nanoparticle,which is typically in the form of a core/shell nanoparticle (preferably,nanocrystal), having any associated organic coating or other material onthe surface of the nanoparticle that is not removed from the surface byordinary solvation. Such composite particles are useful as “quantumdots,” which have a tunable emission in the near ultraviolet (UV) to farinfrared (IR) range as a result of the use of a semiconductor material.

The term “nanoparticle” refers to a particle having an average particlediameter in the range of 0.1 to 1000 nanometers such as in the range of0.1 to 100 nanometers or in the range of 1 to 100 nanometers. The term“diameter” refers not only to the diameter of substantially sphericalparticles but also to the distance along the smallest axis of thestructure. Suitable techniques for measuring the average particlediameter include, for example, scanning tunneling microscopy, lightscattering, and transmission electron microscopy.

A “core” of a nanoparticle is understood to mean a nanoparticle(preferably, a nanocrystal) to which no shell has been applied or to theinner portion of a core/shell nanoparticle. A core of a nanoparticle canhave a homogenous composition or its composition can vary with depthinside the core. Many materials are known and used in corenanoparticles, and many methods are known in the art for applying one ormore shells to a core nanoparticle. The core has a different compositionthan the one more shells. The core typically has a different chemicalcomposition than the shell of the core/shell nanoparticle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic side elevation view of an edge region of anillustrative film article including quantum dots.

FIG. 2 is a flow diagram of an illustrative method of forming a quantumdot film.

FIG. 3 is a schematic illustration of an embodiment of a displayincluding a quantum dot article.

FIG. 4 illustrates the white point (color) measurement system.

DETAILED DESCRIPTION

The present disclosure provides composite particles that containfluorescent semiconductor nanoparticles that can fluoresce when excitedwith actinic radiation. The composite particles can be used in coatingsand films for use in optical displays.

Fluorescent semiconductor nanoparticles emit a fluorescence signal whensuitably excited. They fluoresce at a second wavelength of actinicradiation when excited by a first wavelength of actinic radiation thatis shorter than the second wavelength. In some embodiments, thefluorescent semiconductor nanoparticles can fluoresce in the visibleregion of the electromagnetic spectrum when exposed to wavelengths oflight in the ultraviolet region of the electromagnetic spectrum. Inother embodiments, the fluorescent semiconductor nanoparticles canfluoresce in the infrared region when excited in the ultraviolet orvisible regions of the electromagnetic spectrum. In still otherembodiments, the fluorescent semiconductor nanoparticles can fluorescein the ultraviolet region when excited in the ultraviolet region by ashorter wavelength of light, can fluoresce in the visible region whenexcited by a shorter wavelength of light in the visible region, or canfluoresce in the infrared region when excited by a shorter wavelength oflight in the infrared region. The fluorescent semiconductornanoparticles are often capable of fluorescing in a wavelength rangesuch as, for example, at a wavelength up to 1200 nanometers (nm), or upto 1000 nm, up to 900 nm, or up to 800 nm. For example, the fluorescentsemiconductor nanoparticles are often capable of fluorescence in therange of 400 to 800 nanometers.

The nanoparticles have an average particle diameter of at least 0.1nanometer (nm), or at least 0.5 nm, or at least 1 nm. The nanoparticleshave an average particle diameter of up to 1000 nm, or up to 500 nm, orup to 200 nm, or up to 100 nm, or up to 50 nm, or up to 20 nm, or up to10 nm. Semiconductor nanoparticles, particularly with sizes on the scaleof 1-10 nm, have emerged as a category of the most promising advancedmaterials for cutting-edge technologies.

Semiconductor materials include elements or complexes of Group 2-Group16, Group 12-Group 16, Group 13-Group 15, Group 14-Group 16, and Group14 semiconductors of the Periodic Table (using the modern groupnumbering system of 1-18). Some suitable quantum dots include a metalphosphide, a metal selenide, a metal telluride, or a metal sulfide.Exemplary semiconductor materials include, but are not limited to, Si,Ge, Sn, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN,InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS,ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS,MgSe, MgTe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, Pb Se, PbTe,CuF, CuCl, CuBr, CuI, Si₃N₄, Ge₃N₄, Al₂O₃, (Ga,In)₂(S,Se,Te)₃, Al₂CO,CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, and an appropriatecombination of two or more such semiconductors. These semiconductormaterials can be used for the core, the one or more shell layers, orboth.

In certain embodiments, exemplary metal phosphide quantum dots includeindium phosphide and gallium phosphide, exemplary metal selenide quantumdots include cadmium selenide, lead selenide, and zinc selenide,exemplary metal sulfide quantum dots include cadmium sulfide, leadsulfide, and zinc sulfide, and exemplary metal telluride quantum dotsinclude cadmium telluride, lead telluride, and zinc telluride. Othersuitable quantum dots include gallium arsenide and indium galliumphosphide. Exemplary semiconductor materials are commercially availablefrom Evident Thermoelectrics (Troy, N.Y.), and from Nanosys Inc.,Milpitas, Calif.

Nanocrystals (or other nanostructures) for use in the present inventioncan be produced using any method known to those skilled in the art.Suitable methods are disclosed in U.S. patent application Ser. No.10/796,832, filed Mar. 10, 2004, U.S. Pat. No. 6,949,206 (Whiteford) andU.S. Provisional Patent Application No. 60/578,236, filed Jun. 8, 2004,the disclosures of each of which are incorporated by reference herein intheir entireties. The nanocrystals (or other nanostructures) for use inthe present invention can be produced from any suitable material,suitably an inorganic material, and more suitably an inorganicconductive or semiconductive material. Suitable semiconductor materialsinclude those disclosed in U.S. patent application Ser. No. 10/796,832and include any type of semiconductor, including group II-VI, groupIII-V, group IV-VI and group IV semiconductors.

Suitable semiconductor materials include, but are not limited to, Si,Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP,AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, As,AlSb, GaN, GaP, GaAs, GaSb, ZnO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS,HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe,SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si₃N₄, Ge₃N₄, Al₂O₃,(Ga, In)₂(S, Se, Te)₃, Al₂CO₃ and an appropriate combination of two ormore such semiconductors.

In certain aspects, the semiconductor nanocrystals or othernanostructures may comprise a dopant from the group consisting of: ap-type dopant or an n-type dopant. The nanocrystals (or othernanostructures) useful in the present invention can also comprise Group12-Group 16 or Group 13-Group 15 semiconductors. Examples of Group12-Group 16 or Group 13-Group 15 semiconductor nanocrystals andnanostructures include any combination of an element from Group 12, suchas Zn, Cd and Hg, with any element from Group 16, such as S, Se, Te, Po,of the Periodic Table; and any combination of an element from Group 13,such as B, Al, Ga, In, and Tl, with any element from Group 15, such asN, P, As, Sb and Bi, of the Periodic Table.

Other suitable inorganic nanostructures include metal nanostructures.Suitable metals include, but are not limited to, Ru, Pd, Pt, Ni, W, Ta,Co, Mo, Ir, Re, Rh, Hf, Nb, Au, Ag, Ti, Sn, Zn, Fe, FePt, and the like.

While any known method can be used to create nanocrystal phosphors,suitably, a solution-phase colloidal method for controlled growth ofinorganic nanomaterial phosphors is used. See Alivisatos, A. P.,“Semiconductor clusters, nanocrystals, and quantum dots,” Science271:933 (1996); X. Peng, M. Schlamp, A. Kadavanich, A. P. Alivisatos,“Epitaxial growth of highly luminescent CdSe/CdS Core/Shell nanocrystalswith photostability and electronic accessibility,” J. Am. Chem. Soc.30:7019-7029 (1997); and C. B. Murray, D. J. Norris, M. G. Bawendi,“Synthesis and characterization of nearly monodisperse CdE (E=sulfur,selenium, tellurium) semiconductor nanocrystallites,” J. Am. Chem. Soc.115:8706 (1993). This manufacturing process technology leverages lowcost proccessability without the need for clean rooms and expensivemanufacturing equipment. In these methods, metal precursors that undergopyrolysis at high temperature are rapidly injected into a hot solutionof organic surfactant molecules. These precursors break apart atelevated temperatures and react to nucleate nanocrystals. After thisinitial nucleation phase, a growth phase begins by the addition ofmonomers to the growing crystal. The result is freestanding crystallinenanoparticles in solution that have an organic surfactant moleculecoating their surface.

Utilizing this approach, synthesis occurs as an initial nucleation eventthat takes place over seconds, followed by crystal growth at elevatedtemperature for several minutes. Parameters such as the temperature,types of surfactants present, precursor materials, and ratios ofsurfactants to monomers can be modified so as to change the nature andprogress of the reaction. The temperature controls the structural phaseof the nucleation event, rate of decomposition of precursors, and rateof growth. The organic surfactant molecules mediate both solubility andcontrol of the nanocrystal shape.

In semiconductor nanocrystals, photo-induced emission arises from theband edge states of the nanocrystal. The band-edge emission fromnanocrystals competes with radiative and non-radiative decay channelsoriginating from surface electronic states. X. Peng, et al., J. Am.Chem. Soc. 30:7019-7029 (1997). As a result, the presence of surfacedefects such as dangling bonds provide non-radiative recombinationcenters and contribute to lowered emission efficiency. An efficient andpermanent method to passivate and remove the surface trap states is toepitaxially grow an inorganic shell material on the surface of thenanocrystal. X. Peng, et al., J. Am. Chem. Soc. 30:7019-7029 (1997). Theshell material can be chosen such that the electronic levels are type Iwith respect to the core material (e.g., with a larger bandgap toprovide a potential step localizing the electron and hole to the core).As a result, the probability of non-radiative recombination can bereduced.

Core-shell structures are obtained by adding organometallic precursorscontaining the shell materials to a reaction mixture containing the corenanocrystal. In this case, rather than a nucleation-event followed bygrowth, the cores act as the nuclei, and the shells grow from theirsurface. The temperature of the reaction is kept low to favor theaddition of shell material monomers to the core surface, whilepreventing independent nucleation of nanocrystals of the shellmaterials. Surfactants in the reaction mixture are present to direct thecontrolled growth of shell material and ensure solubility. A uniform andepitaxially grown shell is obtained when there is a low lattice mismatchbetween the two materials. Additionally, the spherical shape acts tominimize interfacial strain energy from the large radius of curvature,thereby preventing the formation of dislocations that could degrade theoptical properties of the nanocrystal system.

In suitable embodiments, ZnS can be used as the shell material usingknown synthetic processes, resulting in a high-quality emission. Asabove, if necessary, this material can be easily substituted, e.g., ifthe core material is modified. Additional exemplary core and shellmaterials are described herein and/or known in the art.

For many applications of quantum dots, two factors are typicallyconsidered in selecting a material. The first factor is the ability toabsorb and emit visible light. This consideration makes InP a highlydesirable base material. The second factor is the material'sphotoluminescence efficiency (quantum yield). Generally, Group 12-16quantum dots (such as cadmium selenide) have higher quantum yield thanGroup 13-15 quantum dots (such as InP). The quantum yield of InP coresproduced previously has been very low (<1%), and therefore theproduction of a core/shell structure with InP as the core and anothersemiconductor compound with higher bandgap (e.g., ZnS) as the shell hasbeen pursued in attempts to improve the quantum yield.

Thus, the fluorescent semiconductor nanoparticles (i.e., quantum dots)of the present disclosure include a core and a shell at least partiallysurrounding the core. The core/shell nanoparticles can have two distinctlayers, a semiconductor or metallic core and a shell surrounding thecore of an insulating or semiconductor material. The core often containsa first semiconductor material and the shell often contains a secondsemiconductor material that is different than the first semiconductormaterial. For example, a first Group 12-16 (e.g., CdSe) semiconductormaterial can be present in the core and a second Group 12-16 (e.g., ZnS)semiconductor material can be present in the shell.

In certain embodiments of the present disclosure, the core includes ametal phosphide (e.g., indium phosphide (InP), gallium phosphide (GaP),aluminum phosphide (AlP)), a metal selenide (e.g., cadmium selenide(CdSe), zinc selenide (ZnSe), magnesium selenide (MgSe)), or a metaltelluride (e.g., cadmium telluride (CdTe), zinc telluride (ZnTe)). Incertain embodiments, the core includes a metal phosphide (e.g., indiumphosphide) or a metal selenide (e.g., cadmium selenide). In certainpreferred embodiments of the present disclosure, the core includes ametal phosphide (e.g., indium phosphide).

The shell can be a single layer or multilayered. In some embodiments,the shell is a multilayered shell. The shell can include any of the corematerials described herein. In certain embodiments, the shell materialcan be a semiconductor material having a higher bandgap energy than thesemiconductor core. In other embodiments, suitable shell materials canhave good conduction and valence band offset with respect to thesemiconductor core, and in some embodiments, the conduction band can behigher and the valence band can be lower than those of the core. Forexample, in certain embodiments, semiconductor cores that emit energy inthe visible region such as, for example, CdS, CdSe, CdTe, ZnSe, ZnTe,GaP, InP, or GaAs, or near IR region such as, for example, InP, InAs,InSb, PbS, or PbSe may be coated with a shell material having a bandgapenergy in the ultraviolet regions such as, for example, ZnS, GaN, andmagnesium chalcogenides such as MgS, MgSe, and MgTe. In otherembodiments, semiconductor cores that emit in the near IR region can becoated with a material having a bandgap energy in the visible regionsuch as CdS or ZnSe.

Formation of the core/shell nanoparticles may be carried out by avariety of methods. Suitable core and shell precursors useful forpreparing semiconductor cores are known in the art and can include Group2 elements, Group 12 elements, Group 13 elements, Group 14 elements,Group 15 elements, Group 16 elements, and salt forms thereof. Forexample, a first precursor may include metal salt (M+X−) including ametal atom (M+) such as, for example, Zn, Cd, Hg, Mg, Ca, Sr, Ba, Ga,In, Al, Pb, Ge, Si, or in salts and a counter ion (X−), ororganometallic species such as, for example, dialkyl metal complexes.The preparation of a coated semiconductor nanocrystal core andcore/shell nanocrystals can be found in, for example, Dabbousi et al.(1997) J. Phys. Chem. B 101:9463, Hines et al. (1996) J. Phys. Chem.100: 468-471, and Peng et al. (1997) J. Amer. Chem. Soc. 119:7019-7029,as well as in U.S. Pat. No. 8,283,412 (Liu et al.) and InternationalPublication No. WO 2010/039897 (Tulsky et al.).

In certain preferred embodiments of the present disclosure, the shellincludes a metal sulfide (e.g., zinc sulfide or cadmium sulfide). Incertain embodiments, the shell includes a zinc-containing compound(e.g., zinc sulfide or zinc selenide). In certain embodiments, amultilayered shell includes an inner shell overcoating the core, whereinthe inner shell includes zinc selenide and zinc sulfide. In certainembodiments, a multilayered shell includes an outer shell overcoatingthe inner shell, wherein the outer shell includes zinc sulfide.

In some embodiments, the core of the shell/core nanoparticle contains ametal phosphide such as indium phosphide, gallium phosphide, or aluminumphosphide. The shell contains zinc sulfide, zinc selenide, or acombination thereof. In some more particular embodiments, the corecontains indium phosphide and the shell is multilayered with the innershell containing both zinc selenide and zinc sulfide and the outer shellcontaining zinc sulfide.

The thickness of the shell(s) may vary among embodiments and can affectfluorescence wavelength, quantum yield, fluorescence stability, andother photostability characteristics of the nanocrystal. The skilledartisan can select the appropriate thickness to achieve desiredproperties and may modify the method of making the core/shellnanoparticles to achieve the appropriate thickness of the shell(s).

The diameter of the fluorescent semiconductor nanoparticles (i.e.,quantum dots) of the present disclosure can affect the fluorescencewavelength. The diameter of the quantum dot is often directly related tothe fluorescence wavelength. For example, cadmium selenide quantum dotshaving an average particle diameter of about 2 to 3 nanometers tend tofluoresce in the blue or green regions of the visible spectrum whilecadmium selenide quantum dots having an average particle diameter ofabout 8 to 10 nanometers tend to fluoresce in the red region of thevisible spectrum.

Since InP may be purified by bonding with dodecylsuccinic acid (DDSA)and lauric acid (LA) first, following by precipitation from ethanol, theprecipitated quantum dots may have some of the acid functional ligandsattached thereto, prior to dispersing in the fluid carrier. Similarly,CdSe quantum dots may be functionalized with amine-functional ligands asresult of their preparation, prior to functionalization with the instantligands. As result, the quantum dots may be functionalized with thosesurface modifying additives or ligands resulting from the originalsynthesis of the nanoparticles.

As result, the quantum dots may be surface modified with ligands ofFormula III:

R⁵—R¹²(X)_(n)  III

whereinR⁵ is (hetero)hydrocarbyl group having C₂ to C₃₀ carbon atoms;R¹² is a hydrocarbyl group including alkylene, arylene, alkarylene andaralkylene;n is at least one;X is a ligand group, including —CO₂H, —SO₃H, —P(O)(OH)₂, —OP(O)(OH), —OHand —NH₂.

Such additional surface modifying ligands may be added when thefunctionalizing with the stabilizing carrier fluids of Formulas I or II,or may be attached to the nanoparticles as result of the synthesis. Suchadditional surface modifying agents are present in amounts less than orequal to the weight of the instant stabilizing carrier fluids,preferably 10 wt. % or less, relative to the amount of the ligands.

Various methods can be used to surface modify the fluorescentsemiconductor nanoparticles with the ligand compounds. In someembodiments, procedures similar to those described in U.S. Pat. No.7,160,613 (Bawendi et al.) and U.S. Pat. No. 8,283,412 (Liu et al.) canbe used to add the surface modifying agent. For example, the ligandcompound and the fluorescent semiconductor nanoparticles can be heatedat an elevated temperature (e.g., at least 50° C., at least 60° C., atleast 80° C., or at least 90° C.) for an extended period of time (e.g.,at least 1 hour, at least 5 hours, at least 10 hours, at least 15 hours,or at least 20 hours).

If desired, any by-product of the synthesis process or any solvent usedin surface-modification process can be removed, for example, bydistillation, rotary evaporation, or by precipitation of thenanoparticles and centrifugation of the mixture followed by decantingthe liquid and leaving behind the surface-modified nanoparticles. Insome embodiments, the surface-modified fluorescent semiconductornanoparticles are dried to a powder after surface-modification. In otherembodiments, the solvent used for the surface modification is compatible(i.e., miscible) with any carrier fluids used in compositions in whichthe nanoparticles are included. In these embodiments, at least a portionof the solvent used for the surface-modification reaction can beincluded in the carrier fluid in which the surface-modified, fluorescentsemiconductor nanoparticles are dispersed.

The fluorescent semiconductor nanoparticles are stabilized using a(meth)acrylate copolymer having pendent phosphine, stibine or arsinegroups. More particularly, the copolymeric stabilizing carrier fluid isof the formula:

˜[M^(ester)]_(a)-[M^(stab)]_(b)-[M^(sil)]_(c)-[M^(acid)]_(d)-[M^(other)]_(e)˜,  IV

where[M^(ester)] represents (meth)acrylate ester monomer units havingsubscript a parts by weight;[M^(stab)] represents monomer units having pendent phosphine, arsine orstibine groups and subscript b parts by weight;[M^(sil)] represents silyl-functional monomer units having subscript cparts by weight;[M^(acid)] represents acid-functional monomer units having subscript dparts by weight; and[M^(other)] represents other monomer units having subscript e parts byweight.

The copolymer may be a random or block copolymer, and the subscriptparts by weight may be normalized to 100 wt. % total monomer.

The monomer units represented by M^(stab) may derived from monomers ofthe formula:

whereinwherein each R¹ is a hydrocarbyl group including alkyl, aryl, alkaryland aralkyl;R² is a divalent hydrocarbyl group selected from alkylene, arylene,alkarylene and aralkylene;

Z is P, As or Sb;

Q is a functional group selected from —CO₂—, —CONR³—, —NH—CO—NR³—, and—NR³—, and each R³ is independently H or C₁-C₄ alkyl, and subscript x is0 or 1. As previously described, one of the R¹ groups may be substitutedfor a groups of the formula —R⁶—Z(R¹)₂. Preferably at least one of theR¹ groups is an aryl group, and more preferably both of the R¹ groupsare aryl groups. In some preferred embodiments R² comprises are arylgroup, an alkaryl group or an aralkyl group.

The monomer units represented by M^(stab) comprises 1-10 parts byweight, preferably 1-5 parts by weight of the copolymer (subscript b).

The copolymeric stabilizing carrier fluid comprises, in part, a(meth)acrylate ester monomer, represented by M^(ester) in Formula IV.Useful acrylic ester monomers include those (meth)acrylic ester of anon-tertiary alcohol, which alcohol contains from 1 to 30 carbon atomsand preferably an average of from 4 to 20 carbon atoms. A mixture ofsuch monomers may be used.

Examples of monomers suitable for use as the (meth)acrylate estermonomer include the esters of either acrylic acid or methacrylic acidwith non-tertiary alcohols such as ethanol, 1-propanol, 2-propanol,1-butanol, 2-butanol, 1-pentanol, 2-pentanol, 3-pentanol,2-methyl-1-butanol, 3-methyl-1-butanol, 1-hexanol, 2-hexanol,2-methyl-1-pentanol, 3-methyl-1-pentanol, 2-ethyl-1-butanol,3,5,5-trimethyl-1-hexanol, 3-heptanol, 1-octanol, 2-octanol,isooctylalcohol, 2-ethyl-1-hexanol, 1-decanol, 2-propylheptanol,1-dodecanol, 1-tridecanol, 1-tetradecanol, citronellol,dihydrocitronellol, and the like. In some embodiments, the preferred(meth)acrylate ester monomer is the ester of (meth)acrylic acid with2-ethylhexyl, butyl or isooctyl alcohol, or a combination thereof,although combinations of two or more different (meth)acrylate estermonomer are suitable.

The copolymeric stabilizing carrier fluid will generally comprise 20-90parts by weight, preferably 25-60 parts by weight of M^(ester) monomerunits (subscript a),

The copolymeric stabilizing carrier fluid optionally contains silanemonomers [M^(Silane)] including those with the following formula:

A-R⁸—[Si—(R⁹)₃]_(q)

wherein:A is an ethylenically unsaturated polymerizable group, including vinyl,allyl, vinyloxy, allyloxy, and (meth)acryloyl, preferably(meth)acrylate;R⁸ is a covalent bond or a divalent (hetero)hydrocarbyl group, q is atleast one, preferably greater than 1, more preferably 3;R⁹ is a monovalent alkyl, aryl or a trialkylsilyloxy group, q is 1, 2 or3, preferably 1.

In one embodiment R⁸ is a di- or polyvalent hydrocarbon bridging groupof about 1 to 20 carbon atoms, including alkylene and arylene andcombinations thereof, optionally including in the backbone 1 to 5moieties selected from the group consisting of —O—, —C(O)—, —S—, —SO₂—and —NR¹— groups (and combinations thereof such as —C(O)—O—), wherein R¹is hydrogen, or a C₁-C₄ alkyl group. Preferably, R⁸ is a divalentalkylene.

Useful silane monomers include, for example, 3-(methacryloyloxy)propyltrimethylsilane, 3-acryloxypropyltrimethylsilane,3-acryloyloxypropyltriethylsilane,3-(methacryloyloxy)propyltriethylsilane,3-(methacryloyloxy)propylmethyldimethylsilane,3-(acryloyloxypropyl)methyldimethylsilane,3-(methacryloyloxy)propyldimethylethylsilane, 3-(methacryloyloxy)propyldiethylethylsilane, vinyldimethylethylsilane,vinylmethyldiethylsilane, vinyltriethylsilane, vinyltriisopropylsilane,vinyltrimethylsilane, vinyltriphenylsilane, vinyltri-t-butylsilane,vinyltris-isobutylsilane, vinyltriisopropenylsilane,vinyltris(2-methylethyl)silane,3-(methacryloyloxy)propyl-tris-trimethylsilyl silane and mixturesthereof.

In other useful embodiments, the silane-functional monomer may beselected from silane functional macromers, such as those disclosed in US2007/0054133 (Sherman et al.) and US 2013/0224373 (Jariwala et al.),incorporated herein by reference and those silicone macromers obtainedfrom Gelest, such as methacryloxypropyl terminatedpolydimethylsiloxanes.

The preparation of silane macromonomer and subsequent co-polymerizationwith vinyl monomer have been described in several papers by Y. Yamashitaet al., Polymer J. 14, 913 (1982); ACS Polymer Preprints 25 (1), 245(1984); Makromol. Chem. 185, 9 (1984), and in U.S. Pat. Nos. 3,786,116and 3,842,059 (Milkovich et al.). This method of macromonomerpreparation involves the anionic polymerization ofhexamethylcyclotrisiloxane monomer to form living polymer of controlledmolecular weight, and termination is achieved via chlorosilane compoundscontaining a polymerizable vinyl group. Free radical co-polymerizationof the monofunctional siloxane macromonomer with vinyl monomer such asmethyl methacrylate or styrene provides siloxane grafted co-polymer ofwell-defined structure, i.e., controlled length and number of graftedsiloxane branches. Such macromers includepoly(3-methacryloyloxypropyltris(trimethylsiloxy)silane (TRIS)-co-methylmethacrylate-co-isooctyl acrylate.

The optional silane monomers [M^(Sil)] are used in amounts of 0 to 70,preferably 1-50, parts by weight, (subscript c) relative to 100 parts byweight total monomer. Such optional silane monomers are used to promotephase separation from the curable binder to achieve optimized opticalperformance.

The copolymer comprises an optional electron donor functional acrylatemonomer, where the electron donor may be the acid functional group,where the acid functional group may be an acid per se, such as acarboxylic acid, or a portion may be salt thereof, such as an alkalimetal carboxylate. Useful acid functional monomers include, but are notlimited to, those selected from ethylenically unsaturated carboxylicacids, ethylenically unsaturated sulfonic acids, ethylenicallyunsaturated phosphonic acids, and mixtures thereof. Examples of suchcompounds include those selected from acrylic acid, methacrylic acid,2-(meth)acryloyloxyethyl succinic acid, 2-acryloyloxyethyl succinicacid, itaconic acid, fumaric acid, crotonic acid, citraconic acid,maleic acid, oleic acid, β-carboxyethyl (meth)acrylate, 2-sulfoethylmethacrylate, styrene sulfonic acid,2-acrylamido-2-methylpropanesulfonic acid, vinylphosphonic acid, andmixtures thereof.

Due to their availability, acid functional monomers of the acidfunctional copolymer are generally selected from ethylenicallyunsaturated carboxylic acids, i.e. (meth)acrylic acids. When evenstronger acids are desired, acidic monomers include the ethylenicallyunsaturated sulfonic acids and ethylenically unsaturated phosphonicacids.

The optional (meth)acrylic acid may be used in amounts such thatsubscript d is 0 to 15 parts by weight, preferably 1 to 10 parts byweight.

The copolymer may further comprise a vinyl monomer, designated asM^(other) in Formula IV. When used, vinyl monomers useful in the(meth)acrylate copolymer include vinyl esters (e.g., vinyl acetate andvinyl propionate), styrene, substituted styrene (e.g., α-methylstyrene), vinyl halide, and mixtures thereof. As used herein vinylmonomers are exclusive of the other recited monomers of Formula IV. Suchvinyl monomers are generally used at 0 to 5 parts by weight, preferably1 to 5 parts by weight, based on 100 parts by weight total monomer.

In some embodiments, the composite particles may further comprises asecondary stabilizing additives of the formula:

wherein R¹ is a hydrocarbyl group, including aryl, alkaryl, alkyl oraralkyl, preferably at least one of R¹ is aryl or alkaryl, morepreferably at least two are aryl or alkaryl; R² is R¹ when a is one anda C₁-C₁₀ divalent alkylene when a is 2; Z is P, As or Sb. Reference maybe made to U.S. 62/234,066, incorporated herein by reference. Suchsecondary stabilizing additives may be used in amounts up to an equalweight of the stabilizing carrier fluid of Formulas I and II.

The copolymer may be synthesized by radical, anionic or cationicpolymerization of the monomers comprising the crystalline monomer andthe amorphous monomer, although synthesis by radical polymerization ispreferred for ease of reaction with a greater variety of usablemonomers. The initiator for the radical polymerization may be a thermalinitiator which generates radicals by heat, or a photoinitiator whichgenerates radicals by light. The degree of conversion (of monomers tocopolymer) can be monitored during the irradiation by measuring theindex of refraction of the polymerizing mixture.

Solventless polymerization methods, such as the continuous free radicalpolymerization method described in U.S. Pat. Nos. 4,619,979 and4,843,134 (Kotnour et al.); the essentially adiabatic polymerizationmethods using a batch reactor described in U.S. Pat. No. 5,637,646(Ellis); and, the methods described for polymerizing packagedpre-adhesive compositions described in U.S. Pat. No. 5,804,610 (Hamer etal.) may also be utilized to prepare the polymers. Preferably, thecopolymeric stabilizer is prepared by the adiabatic batch polymerizationprocess wherein the total of the absolute value of any energy exchangedto or from the batch during the course of reaction will be less thanabout 15% of the total energy liberated due to reaction for thecorresponding amount of polymerization that has occurred during the timethat polymerization has occurred, as described in U.S. Pat. No.5,637,646 (Ellis), incorporated herein by reference.

Examples of thermal initiators which may be used include azo compoundssuch as 2,2′-azobis(2,4-dimethylvaleronitrile),2,2′-azobisisobutyronitrile, 2,2′-azobis(2-methylbutyronitrile),1,1′-azobis(1-cyclohexane-1-carbonylnitrile) anddimethyl-2,2′-azoisobutyrate, as well as peroxides such as benzoylperoxide, lauroyl peroxide and t-butyl peroxypivalate. Examples ofphotoinitiators which may be used include benzoin ethers such as benzoinmethyl ether and benzoin butyl ether, acetophenone derivatives such as2,2-dimethoxy-2-phenylacetophenone and 2,2-diethoxyacetophenone, andacylphosphine oxide and acylphosphonate derivatives such asdiphenyl-2,4,6-trimethylbenzoylphosphine oxide,isopropoxy(phenyl)-2,4,6-trimethylbenzoylphosphine oxide anddimethylpivaloylphosphonate.

A chain transfer agent may also be used during synthesis of thecopolymer to control the molecular weight. Chain transfer agents whichmay be used are mercapto compounds such as dodecylmercaptan and halogencompounds such as carbon tetrabromide. For simplicity, the copolymericcopolymers illustrated herein do not the residue of the chain transferagent.

In some embodiments, multifunctional chain transfer agents having two ormore functional groups can be used to produce compounds having two ormore copolymeric groups. Examples of multi-functional chain transferagents include trimethylolpropane tris(2-mercaptoacetate),trimethylolpropane tris(3-mercaptopropionate), pentaerythritoltetrakis(2-mercaptoacetate), pentaerythritoltetrakis(3-mercaptopropionate), ethylene glycolbis(3-mercaptopropionate), dipentaerythritolhexakis(3-mercaptopropionate), 1,4-butanediol bis(3-mercaptopropionate),tris[2-(3-mercaptopropionyloxy)ethyl]isocyanureate, tetraethylene glycolbis(3-mercaptopropionate), ethylene glycol bisthioglycolate,trimethylolethane trithioglycolate, 1,4-butanediol bis-mercaptoacetate,and glyceryl thioglycolate, or combinations of these materials. Themulti-functional chain transfer agents can also be derived from anα,ω-mercaptoalkane or α,ω-allyl alkane as known in the art and include1, 10-dimercaptodecane, 1, 14-dimercapto tetradecane, 1,10-diallyldecane. Other chain transfer agents comprise α,ω-halogen substitutedalkanes such as α,α,α,ω,ω,ω-hexabromodecane. Reference may be made toU.S. Pat. No. 6,395,804 and U.S. Pat. No. 6,201,099 (Peterson et al.)incorporated herein by reference.

The weight average molecular weight (M_(w)) of the copolymer isgenerally 1000-200,000, preferably 1,500-100,000, more preferably1,500-60,000, and most preferably 2,000-30,000.

The stabilizing carrier fluids of Formulas I and II may function, atleast in part, to reduce the number of aggregated fluorescentsemiconductor nanoparticles within the dispersion composition. Theformation of aggregated fluorescent semiconductor nanoparticles canalter the fluorescent characteristics or quantum efficiency of thedispersion composition.

Composite nanoparticles (i.e., fluorescent semiconductor nanoparticlescombined with the stabilizing carrier fluids) can be used inconventional electronics, semiconductor devices, electrical systems,optical systems, consumer electronics, industrial or militaryelectronics, and nanocrystal, nanowire (NW), nanorod, nanotube, sensingapplications, and light-emitting diode (LED) lighting applications andnanoribbon technologies.

The stabilized nanoparticles comprising the fluorescent semiconductornanoparticles and stabilizing carrier fluid may be dispersed in asolution that contains (a) the copolymeric stabilizing carrier fluid ofFormulas I or II, (b) an optional secondary carrier fluid and (c) apolymeric binder, a precursor of the polymeric binder, or combinationsthereof. The stabilized nanoparticles may be dispersed in thestabilizing carrier fluid, the optional secondary polymeric ornon-polymeric carrier fluid, which is then dispersed in the polymericbinder, forming droplets of the nanoparticles in the carrier fluid,which in turn are dispersed in the polymeric binder.

The secondary carrier fluids are typically selected to be compatible(i.e., miscible) with the stabilizing carrier fluid and optional surfacemodifying ligand of the fluorescent semiconductor nanoparticles.

Suitable secondary carrier fluids include, but are not limited to,aromatic hydrocarbons (e.g., toluene, benzene, or xylene), aliphatichydrocarbons such as alkanes (e.g., cyclohexane, heptane, hexane, oroctane), alcohols (e.g., methanol, ethanol, isopropanol, or butanol),ketones (e.g., acetone, methyl ethyl ketone, methyl isobutyl ketone, orcyclohexanone), aldehydes, amines, amides, esters (e.g., amyl acetate,ethylene carbonate, propylene carbonate, or methoxypropyl acetate),glycols (e.g., ethylene glycol, propylene glycol, butylene glycol,triethylene glycol, diethylene glycol, hexylene glycol, or glycol etherssuch as those commercially available from Dow Chemical, Midland, Mich.under the trade designation DOWANOL), ethers (e.g., diethyl ether),dimethyl sulfoxide, tetramethylsulfone, halocarbons (e.g., methylenechloride, chloroform, or hydrofluoroethers), or combinations thereof.Preferred carrier fluids include aromatic hydrocarbons (for e.g.,toluene), aliphatic hydrocarbons such as alkanes.

The optional secondary non-polymeric carrier fluids are inert, liquid at25° C. and have a boiling point ≥100° C., preferably ≥150° C.; and canbe one or a mixture of liquid compounds. Higher boiling points arepreferred so that the carrier fluids remain when organic solvents usedin the preparation are removed.

In some embodiments the secondary carrier fluid is an oligomeric orpolymeric carrier fluid. The polymeric carriers provide a medium ofintermediate viscosity that is desirable for further processing of theadditive in combination with the fluorescent nanoparticle into a thinfilm. The polymeric carrier is preferably selected to form a homogenousdispersion with the additive combined fluorescent nanoparticle, butpreferably incompatible with the curable polymeric binders. Thepolymeric carriers are liquid at 25° C. and include polysiloxanes, sucha polydimethylsiloxane, liquid fluorinated polymers, includingperfluoropolyethers, (poly(acrylates), polyethers, such as poly(ethyleneglycol), poly(propylene glycol), and poly(butylene glycol). A preferredpolymeric polysiloxane is polydimethylsiloxane.

The polymeric binders or resins desirably provide barrier properties toexclude oxygen and moisture when cured. If water and/or oxygen enter thequantum dot article, the quantum dots can degrade and ultimately fail toemit light when excited by ultraviolet or blue light irradiation.Slowing or eliminating quantum dot degradation along the laminate edgesis particularly important to extend the service life of the displays insmaller electronic devices such as those utilized in, for example,handheld devices and tablets.

Exemplary polymeric binders include, but are not limited to,polysiloxanes, fluoroelastomers, polyamides, polyimides,polycarolactones, polycaprolactams, polyurethanes, polyethers, polyvinylchlorides, polyvinyl acetates, polyesters, polycarbonates,polyacrylates, polymethacrylates, polyacrylamides, andpolymethacrylamides.

Suitable precursors of the polymeric binder or resin include anyprecursor materials used to prepare the polymeric materials listedabove. Exemplary precursor materials include acrylates that can bepolymerized to polyacrylates, methacrylates that can be polymerized toform polymethacrylates, acrylamides that can be polymerized to formpolyacrylamides, methacrylamides that can be polymerized to formpolymethacrylamides, epoxy resins and dicarboxylic acids that can bepolymerized to form polyesters, diepoxides that can be polymerized toform polyethers, isocyanates and polyols that can be polymerized to formpolyurethanes, or polyols and dicarboxylic acids that can be polymerizedto form polyesters.

In some embodiments, such as CdSe, the polymeric binder is a thermallycurable epoxy-amine composition optionally further comprising aradiation-curable acrylate as described in Applicant's copending WO2015095296 (Eckert et al.); Thiol-epoxy resins as described in U.S.62/148,219 (Qiu et al., filed 16 Apr. 2015), thiol-alkene-epoxy resinsas described in U.S. 62/148,212 (Qui et al. filed 16 Apr. 2015);thiol-alkene resins as described in U.S. 62/080,488 (Qui et al., filed17 Nov. 2014), and thiol silicones as described in U.S. 61/950,281 (Qiuet al., filed 10 Mar. 2014).

In some preferred embodiments the polymeric binder is a radiationcurable oligomer having the general formula

R^(Olig)-(L¹-Z¹)_(d), wherein

R^(Olig) groups include urethanes, polyurethanes, esters, polyesters,polyethers, polyolefins, polybutadienes and epoxies;L¹ is a linking group;Z¹ is a pendent, free-radically polymerizable group such as(meth)acryloyl, vinyl or alkynyl and is preferably a (meth)acrylate, andd is greater than 1, preferably at least 2.

The linking group L¹ between the oligomer segment and ethylenicallyunsaturated end group includes a divalent or higher valency groupselected from an alkylene, arylene, heteroalkylene, or combinationsthereof and an optional divalent group selected from carbonyl, ester,amide, sulfonamide, or combinations thereof. L¹ can be unsubstituted orsubstituted with an alkyl, aryl, halo, or combinations thereof. The L¹group typically has no more than 30 carbon atoms. In some compounds, theL¹ group has no more than 20 carbon atoms, no more than 10 carbon atoms,no more than 6 carbon atoms, or no more than 4 carbon atoms. Forexample, L¹ can be an alkylene, an alkylene substituted with an arylgroup, or an alkylene in combination with an arylene or an alkyl etheror alkyl thioether linking group.

The pendent, free radically polymerizable functional groups Z¹ may beselected from the group consisting of vinyl, vinyl ether, ethynyl, and(meth)acyroyl which includes acrylate, methacrylate, acrylamide andmethacrylamide groups.

The oligomeric group R^(olig) may be selected from poly(meth)acrylate,polyurethane, polyepoxide, polyester, polyether, polysulfide,polybutadiene, hydrogenated polyolefins (including hydrogenatedpolybutadienes, isoprenes and ethylene/propylene copolymers, andpolycarbonate oligomeric chains.

As used herein, “(meth)acrylated oligomer” means a polymer moleculehaving at least two pendent (meth)acryloyl groups and a weight averagemolecular weight (M_(w)) as determined by Gel Permeation Chromatographyof at least 1,000 g/mole and typically less than 50,000 g/mole.

(Meth)acryloyl epoxy oligomers are multifunctional (meth)acrylate estersand amides of epoxy resins, such as the (meth)acrylated esters ofbisphenol-A epoxy resin. Examples of commercially available(meth)acrylated epoxies include those known by the trade designationsEBECRYL 600 (bisphenol A epoxy diacrylate of 525 molecular weight),EBECRYL 605 (EBECRYL 600 with 25% tripropylene glycol diacrylate),EBECRYL 3700 (bisphenol-A diacrylate of 524 molecular weight) andEBECRYL 3720H (bisphenol A diacrylate of 524 molecular weight with 20%hexanediol diacrylate) available from Cytec Industries, Inc., WoodlandPark, N.J.; and PHOTOMER 3016 (bisphenol A epoxy acrylate), PHOTOMER3016-40R (epoxy acrylate and 40% tripropylene glycol diacrylate blend),and PHOTOMER 3072 (modified bisphenol A acrylate, etc.) available fromBASF Corp., Cincinnati, Ohio, and Ebecryl 3708 (modified bisphenol Aepoxy diacrylate) available from Cytec Industries, Inc., Woodland Park,N.J.

(Meth)acrylated urethanes are multifunctional (meth)acrylate esters ofhydroxy terminated isocyanate extended polyols, polyesters orpolyethers. (Meth)acrylated urethane oligomers can be synthesized, forexample, by reacting a diisocyanate or other polyvalent isocyanatecompound with a polyvalent polyol (including polyether and polyesterpolyols) to yield an isocyanate terminated urethane prepolymer. Apolyester polyol can be formed by reacting a polybasic acid (e.g.,terephthalic acid or maleic acid) with a polyhydric alcohol (e.g.,ethylene glycol or 1,6-hexanediol). A polyether polyol useful for makingthe acrylate functionalized urethane oligomer can be chosen from, forexample, polyethylene glycol, polypropylene glycol,poly(tetrahydrofuran), poly(2-methyl-tetrahydrofuran),poly(3-methyl-tetrahydrofuran) and the like. Alternatively, the polyollinkage of an acrylated urethane oligomer can be a polycarbonate polyol.

Subsequently, (meth)acrylates having a hydroxyl group can then bereacted with the terminal isocyanate groups of the prepolymer. Botharomatic and the preferred aliphatic isocyanates can be used to reactwith the urethane to obtain the oligomer. Examples of diisocyanatesuseful for making the (meth)acrylated oligomers are 2,4-tolylenediisocyanate, 2,6-tolylene diisocyanate, 1,3-xylylene diisocyanate,1,4-xylylene diisocyanate, 1,6-hexane diisocyanate, isophoronediisocyanate and the like. Examples of hydroxy terminated acrylatesuseful for making the acrylated oligomers include, but are not limitedto, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate,α-hydroxybutyl acrylate, polyethylene glycol (meth)acrylate and thelike.

A (meth)acrylated urethane oligomer can be, for example, any urethaneoligomer having at least two acrylate functionalities and generally lessthan about six functionalities. Suitable (meth)acrylated urethaneoligomers are also commercially available such as, for example, thoseknown by the trade designations PHOTOMER 6008, 6019, 6184 (aliphaticurethane triacrylates) available from Henkel Corp.; EBECRYL 220(hexafunctional aromatic urethane acrylate of 1000 molecular weight),EBECRYL 284 (aliphatic urethane diacrylate of 1200 molecular weightdiluted with 12% of 1,6-hexanediol diacrylate), EBECRYL 4830 (aliphaticurethane diacrylate of 1200 molecular weight diluted with 10% oftetraethylene glycol diacrylate), and EBECRYL 6602 (trifunctionalaromatic urethane acrylate of 1300 molecular weight diluted with 40% oftrimethylolpropane ethoxy triacrylate), available from UCB Chemical; andSARTOMER CN1963, 963E75, 945A60, 963B80, 968, and 983) available fromSartomer Co., Exton, Pa.

Properties of these materials may be varied depending upon selection ofthe type of isocyanate, the type of polyol modifier, the reactivefunctionality and molecular weight. Diisocyanates are widely used inurethane acrylate synthesis and can be divided into aromatic andaliphatic diisocyanates. Aromatic diisocyanates are used for manufactureof aromatic urethane acrylates which have significantly lower cost thanaliphatic urethane acrylates but tend to noticeably yellow on white orlight colored substrates. Aliphatic urethane acrylates include aliphaticdiisocyanates that exhibit slightly more flexibility than aromaticurethane acrylates that include the same functionality, a similar polyolmodifier and at similar molecular weight.

The curable composition may comprise a functionalized poly(meth)acrylateoligomer, which may be obtained from the reaction product of: (a) from50 to 99 parts by weight of (meth)acrylate ester monomer units that arehomo- or co-polymerizable to a polymer (b) from 1 to 50 parts by weightof monomer units having a pendent, free-radically polymerizablefunctional group. Examples of such materials are available from LuciteInternational (Cordova, Tenn.) under the trade designations of Elvacite1010, Elvacite 4026, and Elvacite 4059.

The (meth)acrylated poly(meth)acrylate oligomer may comprise a blend ofan acrylic or hydrocarbon polymer with multifunctional (meth)acrylatediluents. Suitable polymer/diluent blends include, for example,commercially available products such as EBECRYL 303, 745 and 1710 all ofwhich are available from Cytec Industries, Inc., Woodland Park, N.J.

The curable composition may comprise a (meth)acrylated polybutadieneoligomer, which may be obtained from a carboxyl- orhydroxyl-functionalized polybutadiene. By carboxyl or hydroxyfunctionalised polybutadiene is meant to designate a polybutadienecomprising free —OH or —COOH groups. Carboxyl functionalizedpolybutadienes are known, they have for example been described in U.S.Pat. No. 3,705,208 (Nakamuta et al.) and are commercially availableunder the trade name of Nisso PB C-1000 (Nisso America, New York, N.Y.).Carboxyl functionalized polybutadienes can also be obtained by thereaction of a hydroxyl functionalized polybutadiene (that is apolybutadiene having free hydroxyl groups) with a cyclic anhydride suchas for example has been described in U.S. Pat. No. 5,587,433(Boeckeler), U.S. Pat. No. 4,857,434 (Klinger) and U.S. Pat. No.5,462,835 (Mirle).

Carboxyl and hydroxyl functionalized polybutadienes suitable for beingused in the process according to the present invention contain besidesthe carboxyl and/or hydroxyl groups, units derived from thepolymerization of butadiene. The polybutadiene (PDB) generally comprises1-4 cis units/1-4 trans units/1-2 units in a ratio a/b/c where a, b andc range from 0 to 1 with a+b+c=1. The number average molecular weight(M_(n)) of the functionalized polybutadiene is preferably from 200 to10000 Da. The M_(n) is more preferably at least 1000. The M_(n) morepreferably does not exceed 5000 Da. The —COOH or —OH functionality isgenerally from 1.5 to 9, preferably from 1.8 to 6.

Exemplary hydroxyl and carboxyl polybutadienes include withoutlimitation Poly BD R-20LM (hydroxyl functionalized PDB, a=0.2, b=0.6,c=0.2, M_(n) 1230) and Poly BD R45-HT (hydroxyl functionalized PDB,a=0.2, b=0.6, c=0.2, M_(n) 2800) commercialized by Atofina, Nisso-PBG-1000 (hydroxyl functionalized PDB, a=0, b<0.15, c>0.85, M_(n)1250-1650), Nisso-PB G-2000 (hydroxyl functionalized PDB, a=0, b<0.15,c>0.85, M_(n) 1800-2200), Nisso-PB G-3000 (hydroxyl functionalized PDB,a=0, b<0.10, c>0.90, M_(n) 2600-3200), Nisso-PB C-1000 (carboxylfunctionalized PDB, a=0, b<0.15, c>0.85, M_(n) 1200-1550) obtainablefrom Nisso America, New York, N.Y.

When carboxyl functionalized polybutadienes obtained from the reactionof a hydroxyl functionalized polybutadiene with a cyclic anhydride areused, this cyclic anhydride preferably include phthalic anhydride,hexahydrophthalic anhydride, glutaric anhydride, succinic anhydride,dodecenylsuccinic anhydride, maleic anhydride, trimellitic anhydride,pyromellitic anhydride. Mixtures of anhydrides can also be used. Theamount of anhydride used for the preparation of a carboxylfunctionalized polybutadiene from a hydroxyl functionalizedpolybutadiene is generally at least 0.8 molar, preferably at least 0.9molar and more preferably at least 0.95 molar equivalent per molarequivalents of —OH groups present in the polybutadiene.

A (meth)acrylated polybutadiene oligomer, which is the reaction productof a carboxyl functionalized polybutadiene, may be prepared with a(meth)acrylated monoepoxide. (Meth)acrylated mono-epoxides are known.Examples of (meth)acrylated mono-epoxides that can be used are glycidyl(meth)acrylate esters, such as glycidylacrylate, glycidylmethacrylate,4-hydroxybutylacrylate glycidylether, bisphenol-A diglycidylethermonoacrylate. The (meth)acrylated mono-epoxides are preferably chosenfrom glycidylacrylate and glycidylmethacrylate. Alternatively, a(meth)acrylated polybutadiene oligomer which is the reaction product ofa hydroxyl functionalized polybutadiene may be prepared with a(meth)acrylate ester, or halide.

Some (meth)acrylated polybutadienes that can be used, for example,include Ricacryl 3100 and Ricacryl 3500, manufactured by SartomerCompany, Exton, Pa., USA, and Nisso TE-2000 available from NissoAmerica, New York, N.Y. Alternatively, other methacrylatedpolybutadienes can be used. These include dimethacrylates of liquidpolybutadiene resins composed of modified, esterified liquidpolybutadiene diols. These are available under the tradename CN301 andCN303, and CN307, manufactured by Sartomer Company, Exton, Pa., USA.Regardless which methacrylated polybutadiene is used with embodiments ofthe invention, the methacrylated polybutadiene can include a number ofmethacrylate groups per chain from about 2 to about 20.

Alternatively, the acrylate functionalized oligomers can be polyesteracrylate oligomers, acrylated acrylic oligomers, acrylated epoxyoligomers, polycarbonate acrylate oligomers or polyether acrylateoligomers. Useful epoxy acrylate oligomers include CN2003B from SartomerCo. (Exton, Pa.). Useful polyester acrylate oligomers include CN293,CN294, and CN2250, 2281, 2900 from Sartomer Co. (Exton, Pa.) and EBECRYL80, 657, 830, and 1810 from UCB Chemicals (Smyrna, Ga.). Suitablepolyether acrylate oligomers include CN501, 502, and 551 from SartomerCo. (Exton, Pa.). Useful polycarbonate acrylate oligomers can beprepared according to U.S. Pat. No. 6,451,958 (Sartomer TechnologyCompany Inc., Wilmington, Del.).

In each embodiment comprising a (meth)acrylated oligomer, the curablebinder composition optionally, yet preferably, comprises diluent monomerin an amount sufficient to reduce the viscosity of the curablecomposition such that it may be coated on a substrate. In someembodiments, the composition may comprise up to about 70 wt-% diluentmonomers to reduce the viscosity of the oligomeric component to lessthan 10000 centipoise and to improve the processability.

Useful monomers are desirably soluble or miscible in the (meth)acrylatedoligomer, highly polymerizable therewith. Useful diluents are mono- andpolyethylenically unsaturated monomers such as (meth)acrylates or(meth)acrylamides. Suitable monomers typically have a number averagemolecular weight no greater than 450 g/mole. The diluent monomerdesirably has minimal absorbance at the wavelength of the radiation usedto cure the composition. Such diluent monomers may include, for example,n-butyl acrylate, isobutyl acrylate, hexyl acrylate,2-ethyl-hexylacrylate, isooctylacrylate, caprolactoneacrylate,isodecylacrylate, tridecylacrylate, laurylmethacrylate,methoxy-polyethylenglycol-monomethacrylate, laurylacrylate,tetrahydrofurfuryl-acrylate, ethoxy-ethoxyethyl acrylate andethoxylated-nonylacrylate. Especially preferred are2-ethyl-hexylacrylate, ethoxy-ethoxyethyl acrylate, tridecylacrylate andethoxylated nonylacrylate. High T_(g) monomers having one ethylenicallyunsaturated group and a glass transition temperature of thecorresponding homopolymer of 50° C. or more which are suitable in thepresent invention, include, for example, N-vinylpyrrolidone, N-vinylcaprolactam, isobornyl acrylate, acryloylmorpholine,isobornylmethacrylate, phenoxyethylacrylate, phenoxyethylmethacrylate,methylmethacrylate and acrylamide.

Furthermore, the diluent monomers may contain an average of two or morefree-radically polymerizable groups. A diluent having three or more ofsuch reactive groups can be present as well. Examples of such monomersinclude: C₂-C₁₈ alkylenedioldi(meth)acrylates, C₃-C₁₈alkylenetrioltri(meth)acrylates, the polyether analogues thereof, andthe like, such as 1,6-hexanedioldi(meth)acrylate,trimethylolpropanetri(meth)acrylate, triethyleneglycoldi(meth)acrylate,pentaeritritoltri(meth)acrylate, and tripropyleneglycoldi(meth)acrylate, and di-trimethylolpropane tetraacrylate.

Suitable preferred diluent monomers include for example benzyl(meth)acrylate, phenoxyethyl (meth)acrylate; phenoxy-2-methylethyl(meth)acrylate; phenoxyethoxyethyl (meth)acrylate, 1-naphthyloxy ethylacrylate; 2-naphthyloxy ethyl acrylate; phenoxy 2-methylethyl acrylate;phenoxyethoxyethyl acrylate; 2-phenylphenoxy ethyl acrylate;4-phenylphenoxy ethyl acrylate; and phenyl acrylate.

Preferred diluent monomers includes phenoxyethyl (meth)acrylate, benzyl(meth)acrylate, and tricyclodecane dimethanol diacrylate. Phenoxyethylacrylate is commercially available from Sartomer under the tradedesignation “SR339”; from Eternal Chemical Co. Ltd. under the tradedesignation “Etermer 210”; and from Toagosei Co. Ltd under the tradedesignation “TO-1166”. Benzyl acrylate is commercially available fromOsaka Organic Chemical, Osaka City, Japan. Tricyclodecane dimethanoldiacrylate is commercially available from Sartomer under the tradedesignation “SR833 S”.

Such optional monomer(s) may be present in the polymerizable compositionin amount of at least about 5 wt-%. The optional monomer(s) typicallytotal no more than about 70 wt-% of the curable composition. The someembodiments the total amount of diluent monomer ranges from about 10wt-% to about 50-%.

When using a free-radically curable polymeric binder, the curablecomposition further comprises photoinitiators, in an amount between therange of about 0.1% and about 5% by weight.

Useful photoinitiators include those known as useful for photocuringfree-radically polyfunctional (meth)acrylates. Exemplary photoinitiatorsinclude benzoin and its derivatives such as alpha-methylbenzoin;alpha-phenylbenzoin; alpha-allylbenzoin; alpha-benzylbenzoin; benzoinethers such as benzil dimethyl ketal (e.g., “IRGACURE 651” from BASF,Florham Park, N.J.), benzoin methyl ether, benzoin ethyl ether, benzoinn-butyl ether; acetophenone and its derivatives such as2-hydroxy-2-methyl-1-phenyl-1-propanone (e.g., “DAROCUR 1173” from BASF,Florham Park, N.J.) and 1-hydroxycyclohexyl phenyl ketone (e.g.,“IRGACURE 184” from BASF, Florham Park, N.J.);2-methyl-1-[4-(methylthio)phenyl]-2-(4-morpholinyl)-1-propanone (e.g.,“IRGACURE 907” from BASF, Florham Park, N.J.);2-benzyl-2-(dimethylamino)-1-[4-(4-morpholinyl)phenyl]-1-butanone (e.g.,“IRGACURE 369” from BASF, Florham Park, N.J.) and phosphine oxidederivatives such as ethyl-2,4,6-trimethylbenzoylphenylphoshinate (e.g.“TPO-L” from BASF, Florham Park, N.J.), and IRGACURE 819(phenylbis(2,4,6-trimethylbenzoyl)phosphine oxide) available from BASF,Florham Park, N.J.

Other useful photoinitiators include, for example, pivaloin ethyl ether,anisoin ethyl ether, anthraquinones (e.g., anthraquinone,2-ethylanthraquinone, 1-chloroanthraquinone, 1,4-dimethylanthraquinone,1-methoxyanthraquinone, or benzanthraquinone), halomethyltriazines,benzophenone and its derivatives, iodonium salts and sulfonium salts,titanium complexes such asbis(eta₅-2,4-cyclopentadien-1-yl)-bis[2,6-difluoro-3-(1H-pyrrol-1-yl)phenyl]titanium (e.g., “CGI 784DC” from BASF, Florham Park, N.J.);halomethyl-nitrobenzenes (e.g., 4-bromomethylnitrobenzene), mono- andbis-acylphosphines (e.g., “IRGACURE 1700”, “IRGACURE 1800”, “IRGACURE1850”, and “DAROCUR 4265”).

In some embodiments, the polymeric binder is an epoxy compound that canbe cured or polymerized by the processes that are those known to undergocationic polymerization and include 1,2-, 1,3-, and 1,4-cyclic ethers(also designated as 1,2-, 1,3-, and 1,4-epoxides). Suitable epoxybinders can include, for example, those epoxy binders described in U.S.Pat. No. 6,777,460. In particular, cyclic ethers that are useful includethe cycloaliphatic epoxies such as cyclohexene oxide and the ERL™ andUVR™ series type of binders available from Dow Chemical, Midland, Mich.,such as vinylcyclohexene oxide, vinylcyclohexene dioxide,3,4-epoxycyclohexylmethyl-3, 4-epoxycyclohexane carboxylate,bis-(3,4-epoxycyclohexyl) adipate and 2-(3, 4-epoxycylclohexyl-5,5-spiro-3,4-epoxy) cyclohexene-meta-dioxane; also included are theglycidyl ether type epoxy binders such as propylene oxide,epichlorohydrin, styrene oxide, glycidol, the EPON, EPONEX, and HELOXYseries type of epoxy binders available from Resolution PerformanceProducts, Houston, Tex., including the diglycidyl either of bisphenol Aand chain extended versions of this material such as EPON 828, EPON1001, EPON 1004, EPON 1007, EPON 1009 and EPON 2002 or their equivalentfrom other manufacturers, EPONEX 1510, the hydrogenated diglycidyleither of bisphenol A, HELOXY 67, diglycidyl ether of 1,4-butanediol,HELOXY′ 107, diglycidyl ether of cyclohexane dimethanol, or theirequivalent from other manufacturers, dicyclopentadiene dioxide,epoxidized vegetable oils such as epoxidized linseed and soybean oilsavailable as VIKOLOX and VIKOFLEX binders from Atofina, Philadelphia,Pa., epoxidized KRATON LIQUID POLYMERS, such as L-207 available fromKraton Polymers, Houston, Tex., epoxidized polybutadienes such as thePOLY BD binders from Atofina, Philadelphia, Pa., 1,4-butanedioldiglycidyl ether, polyglycidyl ether of phenolformaldehyde, and forexample DEN™ epoxidized phenolic novolac binders such as DEN 431 and DEN438 available from Dow Chemical Co., Midland Mich., epoxidized cresolnovolac binders such as ARALDITE ECN 1299 available from Vantico AG,Basel, Switzerland, resorcinol diglycidyl ether, and epoxidizedpolystyrene/polybutadiene blends such as the Epofriendz binders such asEPOFRIEND A1010 available from Daicel USA Inc., Fort Lee, N.J., andresorcinol diglycidyl ether.

Higher molecular weight polyols include the polyethylene andpolypropylene oxide polymers in the molecular weight (Mn) range of 200to 20,000 such as the CARBOWAX polyethyleneoxide materials availablefrom Dow Chemical Co., Midland, Mich., caprolactone polyols in themolecular weight range of 200 to 5,000 such as the TONE polyol materialsavailable from Dow, polytetramethylene ether glycol in the molecularweight range of 200 to 4,000, such as the TERATHANE materials availablefrom DuPont and POLYTHF 250 from BASF, polyethylene glycol, such as PEG™200 available from Dow, hydroxyl-terminated polybutadiene binders suchas the POLY BD materials available from Atofina, Philadelphia, Pa.,phenoxy binders such as those commercially available from PhenoxyAssociates, Rock Hill, S.C., or equivalent materials supplied by othermanufacturers.

It is also within the scope of this invention to include one or moreepoxy binders which can be blended together. It is also within the scopeof this invention to include one or more mono or poly-alcohols which canbe blended together. The different kinds of binders and alcohols can bepresent in any proportion.

It is within the scope of this invention to use vinyl ether monomers asthe cationically curable material. Vinyl ether-containing monomers canbe methyl vinyl ether, ethyl vinyl ether, tert-butyl vinyl ether,isobutyl vinyl ether, triethyleneglycol divinyl ether (RAPT-CURE DVE-3,available from International Specialty Products, Wayne, N.J.),1,4-cyclohexanedimethanol divinyl ether (RAPI-CURE CHVE, InternationalSpecialty Products), trimetylolpropane trivinyl ether (available fromBASF Corp., Mount Olive, N.J.) and the VECTOMER divinyl ether bindersfrom Morflex, Greensboro, N.C., such as VECTOMER 2010, VECTOMER 2020,VECTOMER 4010, and VECTOMER 4020, or their equivalent from othermanufacturers. It is within the scope of this invention to use a blendof more than one vinyl ether binder.

It is also within the scope of this invention to use one or more epoxybinders blended with one or more vinyl ether binders. The differentkinds of binders can be present in any proportion.

The preferred epoxy binders include the ERL and the UVR type of bindersespecially 3,4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate,bis-(3,4-epoxycyclohexyl) adipate and 2-(3,4-epoxycylclohexyl-5,5-spiro-3, 4-epoxy) cyclohexene-meta-dioxane andthe bisphenol A EPON type binders including 2,2-bis-p-(2,3-epoxypropoxy) phenylpropane and chain extended versions of thismaterial and, binders of the type EPONEX 1510 and HELOXY 107 and 68.Also useful in the present invention are purified versions of theseepoxies as described in U. S. Published Patent Application 2002/0022709published 21 Feb. 2002.

When preparing compositions containing epoxy monomers,hydroxy-functional materials can be added. The hydroxyl-functionalcomponent can be present as a mixture or a blend of materials and cancontain mono- and polyhydroxyl containing materials. Preferably, thehydroxy-functional material is at least a diol. When used, thehydroxyl-functional material can aid in chain extension and inpreventing excess crosslinking of the epoxy during curing, e. g.,increasing the toughness of the cured composition.

When present, useful hydroxyl-functional materials include aliphatic,cycloaliphatic or alkanol-substituted arene mono- or poly-alcoholshaving from about 2 to about 18 carbon atoms and two to five, preferablytwo to four hydroxy groups, or combinations thereof. Usefulmono-alcohols can include methanol, ethanol, 1-propanol, 2-propanol,2-methyl-2-propanol, 1-butanol, 2-butanol, 1-pentanol, neopentylalcohol, 3-pentanol, 1-hexanol, 1-heptanol, 1-octanol, 2-phenoxyethanol,cyclopentanol, cyclohexanol, cyclohexylmethanol,3-cyclohexyl-1-propanol, 2-norbornanemethanol and tetrahydrofurfurylalcohol.

Polyols useful in the present invention include aliphatic,cycloaliphatic, or alkanol-substituted arene polyols, or mixturesthereof having from about 2 to about 18 carbon atoms and two to five,preferably two to four hydroxyl groups. Examples of useful polyolsinclude 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol,1,4-butanediol, 1,3-butanediol, 2-methyl-1, 3-propanediol, 2,2-dimethyl-1, 3-propanediol, 2-ethyl-1, 6-hexanediol, 1,5-pentanediol,1,6-hexanediol, 1,8-octanediol, neopentyl glycol, glycerol,trimethylolpropane, 1,2, 6-hexanetriol, trimethylolethane,pentaerythritol, quinitol, mannitol, sorbitol, diethylene glycol,triethylene glycol, tetraethylene glycol, glycerine,2-ethyl-2-(hydroxymethyl)-1, 3-propanediol, 2-ethyl-1, 3-pentanediol,1,4-cyclohexanedimethanol, 1,4-benzene-dimethanol and polyalkoxylatedbisphenol A derivatives. Other examples of useful polyols are disclosedin U.S. Pat. No. 4,503,211.

Bi-functional monomers having both cationically polymerizable andfree-radically polymerizable moieties in the same monomer are useful inthe present invention, such as, for example, glycidyl methacrylate, or2-hydroxyethyl acrylate.

It is also within the scope of this invention to add a free radicallypolymerizable monomer, such as an acrylate or methacrylate. The additionof such a monomer broadens the scope of obtainable physical propertiesand processing options. When two or more polymerizable monomers arepresent, they can be present in any proportion.

Suitable cationic photoinitiators are selected from organic oniumcations, for example those described in photoinitiators for Free RadicalCationic & Anionic Photopolymerization, 2′˜d Edition, J. V. Crivello &K. Dietliker, John Wiley and Sons, 1998, pp. 275 to 298, and U.S. Pat.Nos. 4,250,311, 3,708,296, 4,069,055, 4,216,288, 5,084,586 and 5,124,417and such descriptions incorporated herein by reference, includingaliphatic or aromatic Group IVA-VIIA (CAS version) centered onium salts,preferably I-, S-, P- and C-centered onium salts, such as those selectedfrom sulfoxonium, diaryliodonium, triarylsulfonium, carbonium andphosphonium, and most preferably I-, and S-centered onium salts, such asthose selected from sulfoxonium, diaryliodonium, and triarylsulfonium,wherein “aryl” means an unsubstituted or substituted aromatic moietyhaving up to four independently selected substituents.

The quantum dot layer can have any useful amount of quantum dots, and insome embodiments the quantum dot layer can include from 0.1 wt. % to 10wt. % quantum dots, based on the total weight of the quantum dot layer(dots and polymeric binder). In some embodiments, the stabilized quantumdots are added to the fluid carrier in amounts such that the opticaldensity is at least 10, optical density defined as the absorbance at 440nm for a cell with a path length of 1 cm) solution.

The dispersion composition can also contain a surfactant (i.e., levelingagent), a polymerization initiator, and other additives, as known in theart.

Generally, the stabilizing carrier fluid, /quantum dots, optionalsurface-modifying ligand, the polymeric binder and carrier fluids(polymeric or non-polymeric) are combined and subject to high shearmixing to produce a dispersion. The polymeric binder is chosen such thatthere is limited compatibility and the carrier fluid form a separate,non-aggregating phase in the polymeric binder. The dispersion,comprising droplets of carrier fluid containing the nanoparticles andstabilizing carrier fluid dispersed in the polymeric binder, is thencoated and cured either thermally, free-radically, or both to lock inthe dispersed structure and exclude oxygen and water from the dispersedquantum dots.

The curable composition comprising a free radically polymerizablepolymeric binder may be irradiated with activating UV or visibleradiation to polymerize the components preferably in the wavelengths of250 to 500 nanometers. UV light sources can be of two types: 1)relatively low light intensity sources such as blacklights that providegenerally 10 mW/cm² or less (as measured in accordance with proceduresapproved by the United States National Institute of Standards andTechnology as, for example, with a UVIMAP™ UM 365 L-S radiometermanufactured by Electronic Instrumentation & Technology, Inc., inSterling, Va.) over a wavelength range of 280 to 400 nanometers and 2)relatively high light intensity sources such as medium- andhigh-pressure mercury arc lamps, electrodeless mercury lamps, lightemitting diodes, mercury-xenon lamps, lasers and the like, which provideintensities generally between 10 and 5000 mW/cm² in the wavelength ragesof 320-390 nm (as measured in accordance with procedures approved by theUnited States National Institute of Standards and Technology as, forexample, with a PowerPuck™ radiometer manufactured by ElectronicInstrumentation & Technology, Inc., in Sterling, Va.).

Referring to FIG. 1, quantum dot article 10 includes a first barrierlayer 32, a second barrier layer 34, and a quantum dot layer 20 betweenthe first barrier layer 32 and the second barrier layer 34. The quantumdot layer 20 includes a plurality of quantum dots 22 dispersed in apolymeric binder 24, which may be cured or uncured.

The quantum dot layer can have any useful amount of quantum dots. Insome embodiments, the quantum dots are added to the fluid carrier inamounts such that the optical density is at least 10, optical densitydefined as the absorbance at 440 nm for a cell with a path length of 1cm) solution.

The barrier layers 32, 34 can be formed of any useful material that canprotect the quantum dots 22 from exposure to environmental contaminatessuch as, for example, oxygen, water, and water vapor. Suitable barrierlayers 32, 34 include, but are not limited to, films of polymers, glassand dielectric materials. In some embodiments, suitable materials forthe barrier layers 32, 34 include, for example, polymers such aspolyethylene terephthalate (PET); oxides such as silicon oxide, titaniumoxide, or aluminum oxide (e.g., SiO₂, Si₂O₃, TiO₂, or Al₂O₃); andsuitable combinations thereof.

More particularly, barrier films can be selected from a variety ofconstructions. Barrier films are typically selected such that they haveoxygen and water transmission rates at a specified level as required bythe application. In some embodiments, the barrier film has a water vaportransmission rate (WVTR) less than about 0.005 g/m²/day at 38° C. and100% relative humidity; in some embodiments, less than about 0.0005g/m²/day at 38° C. and 100% relative humidity; and in some embodiments,less than about 0.00005 g/m²/day at 38° C. and 100% relative humidity.In some embodiments, the flexible barrier film has a WVTR of less thanabout 0.05, 0.005, 0.0005, or 0.00005 g/m²/day at 50° C. and 100%relative humidity or even less than about 0.005, 0.0005, 0.00005g/m²/day at 85° C. and 100% relative humidity. In some embodiments, thebarrier film has an oxygen transmission rate of less than about 0.005g/m²/day at 23° C. and 90% relative humidity; in some embodiments, lessthan about 0.0005 g/m²/day at 23° C. and 90% relative humidity; and insome embodiments, less than about 0.00005 g/m²/day at 23° C. and 90%relative humidity.

Exemplary useful barrier films include inorganic films prepared byatomic layer deposition, thermal evaporation, sputtering, and chemicalvapor deposition. Useful barrier films are typically flexible andtransparent. In some embodiments, useful barrier films compriseinorganic/organic. Flexible ultra-barrier films comprisinginorganic/organic multilayers are described, for example, in U.S. Pat.No. 7,018,713 (Padiyath et al.). Such flexible ultra-barrier films mayhave a first polymer layer disposed on polymeric film substrate that isovercoated with two or more inorganic barrier layers separated by atleast one second polymer layer. In some embodiments, the barrier filmcomprises one inorganic barrier layer interposed between the firstpolymer layer disposed on the polymeric film substrate and a secondpolymer layer 224.

In some embodiments, each barrier layer 32, 34 of the quantum dotarticle 10 includes at least two sub-layers of different materials orcompositions. In some embodiments, such a multi-layered barrierconstruction can more effectively reduce or eliminate pinhole defectalignment in the barrier layers 32, 34, providing a more effectiveshield against oxygen and moisture penetration into the cured polymericbinder 24. The quantum dot article 10 can include any suitable materialor combination of barrier materials and any suitable number of barrierlayers or sub-layers on either or both sides of the quantum dot layer20. The materials, thickness, and number of barrier layers andsub-layers will depend on the particular application, and will suitablybe chosen to maximize barrier protection and brightness of the quantumdots 22 while minimizing the thickness of the quantum dot article 10. Insome embodiments each barrier layer 32, 34 is itself a laminate film,such as a dual laminate film, where each barrier film layer issufficiently thick to eliminate wrinkling in roll-to-roll or laminatemanufacturing processes. In one illustrative embodiment, the barrierlayers 32, 34 are polyester films (e.g., PET) having an oxide layer onan exposed surface thereof.

The quantum dot layer 20 can include one or more populations of quantumdots or quantum dot materials 22. Exemplary quantum dots or quantum dotmaterials 22 emit green light and red light upon down-conversion of blueprimary light from a blue LED to secondary light emitted by the quantumdots. The respective portions of red, green, and blue light can becontrolled to achieve a desired white point for the white light emittedby a display device incorporating the quantum dot article 10. Exemplaryquantum dots 22 for use in the quantum dot articles 10 include, but arenot limited to, InP with ZnS shells. Suitable quantum dots for use inquantum dot articles described herein include, but are not limited to,core/shell fluorescent nanocrystals including CdSe/ZnS, InP/ZnS,PbSe/PbS, CdSe/CdS, CdTe/CdS or CdTe/ZnS.

In exemplary embodiments, the nanoparticles include a stabilizing fluidcarrier and are dispersed in a cured polymeric binder. Quantum dot andquantum dot materials 22 are commercially available from, for example,Nanosys Inc., Milpitas, Calif.

In one or more embodiments the quantum dot layer 20 can optionallyinclude scattering beads or particles. These scattering beads orparticles have a refractive index that differs from the refractive indexof the cured polymeric binder 24 by at least 0.05, or by at least 0.1.These scattering beads or particles can include, for example, polymerssuch as silicone, acrylic, nylon, and the like, or inorganic materialssuch as TiO₂, SiO_(x), AlO_(x), and the like, and combinations thereof.In some embodiments, including scattering particles in the quantum dotlayer 20 can increase the optical path length through the quantum dotlayer 20 and improve quantum dot absorption and efficiency. In manyembodiments, the scattering beads or particles have an average particlesize from 1 to 10 micrometers, or from 2 to 6 micrometers. In someembodiments, the quantum dot material 20 can optionally include fillerssuch fumed silica.

In some preferred embodiments, the scattering beads or particles areTospearl™ 120A, 130A, 145A and 2000B spherical silicone resins availablein 2.0, 3.0, 4.5 and 6.0 micron particle sizes respectively fromMomentive Specialty Chemicals Inc., Columbus, Ohio.

The cured polymeric binder 24 of the quantum dot layer 20 can be formedfrom a polymeric binder or binder precursor that adheres to thematerials forming the barrier layers 32, 34 to form a laminateconstruction, and also forms a protective matrix for the quantum dots22. In one embodiment, the cured polymeric binder 24 is formed by curingan epoxy amine polymer and an optional radiation-curable methacrylatecompound.

Referring to FIG. 2, in another aspect, the present disclosure isdirected to a method of forming a quantum dot film article 100 includingcoating a polymeric binder composition including quantum dots on a firstbarrier layer 102 and disposing a second barrier layer on the quantumdot material 104. In some embodiments, the method 100 includespolymerizing (e.g., radiation curing) a radiation curable polymericbinder to form a fully- or partially cured quantum dot material 106 andoptionally thermally polymerizing the binder composition to form a curedpolymeric binder 108. For thermally curable polymeric binders, step 106is omitted.

In some embodiments, the binder composition can be cured or hardened byheating. In other embodiments, the binder composition may also be curedor hardened by applying radiation such as, for example, ultraviolet (UV)light. Curing or hardening steps may include UV curing, heating, orboth. In some example embodiments that are not intended to be limiting,UV cure conditions can include applying about 10 mJ/cm² to about 4000mJ/cm² of UVA, more preferably about 10 mJ/cm² to about 1000 mJ/cm² ofUVA. Heating and UV light may also be applied alone or in combination toincrease the viscosity of the binder composition, which can allow easierhandling on coating and processing lines.

In some embodiments, the binder composition may be cured afterlamination between the overlying barrier films 32, 34. Thus, theincrease in viscosity of the binder composition locks in the coatingquality right after lamination. By curing right after coating orlaminating, in some embodiments the cured binder increases in viscosityto a point that the binder composition acts as a pressure sensitiveadhesive (PSA) to hold the laminate together during the cure and greatlyreduces defects during the cure. In some embodiments, the radiation cureof the binder provides greater control over coating, curing and webhandling as compared to traditional thermal curing.

Once at least partially cured, the binder composition forms polymernetwork that provides a protective supporting cured polymeric binder 24for the quantum dots 22.

Ingress, including edge ingress, is defined by a loss in quantum dotperformance due to ingress of moisture and/or oxygen into the curedpolymeric binder 24. In various embodiments, the edge ingress ofmoisture and oxygen into the cured binder 24 is less than about 1.25 mmafter 1 week at 85° C., or about less than 0.75 mm after 1 week at 85°C., or less than about 0.5 mm after 1 week at 85° C. In variousembodiments, oxygen permeation into the cured polymeric binder is lessthan about 80 (cc·mil)/(m² day), or less than about 50 (cc·mil)/(m²day). In various embodiments, the water vapor transmission rate of thecured polymeric binder should be less than about 15 (20 g/m²·mil·day),or less than about 10 (20 g/m²·mil·day).

In various embodiments, the thickness of the quantum dot layer 20 isabout 80 microns to about 250 microns.

FIG. 3 is a schematic illustration of an embodiment of a display device200 including the quantum dot articles described herein. Thisillustration is merely provided as an example and is not intended to belimiting. The display device 200 includes a backlight 202 with a lightsource 204 such as, for example, a light emitting diode (LED). The lightsource 204 emits light along an emission axis 235. The light source 204(for example, a LED light source) emits light through an input edge 208into a hollow light recycling cavity 210 having a back reflector 212thereon. The back reflector 212 can be predominately specular, diffuseor a combination thereof, and is preferably highly reflective. Thebacklight 202 further includes a quantum dot article 220, which includesa protective binder 224 having dispersed therein quantum dots 222. Theprotective cured polymeric binder 224 is bounded on both surfaces bypolymeric barrier films 226, 228, which may include a single layer ormultiple layers.

The display device 200 further includes a front reflector 230 thatincludes multiple directional recycling films or layers, which areoptical films with a surface structure that redirects off-axis light ina direction closer to the axis of the display, which can increase theamount of light propagating on-axis through the display device, thisincreasing the brightness and contrast of the image seen by a viewer.The front reflector 230 can also include other types of optical filmssuch as polarizers. In one non-limiting example, the front reflector 230can include one or more prismatic films 232 and/or gain diffusers. Theprismatic films 232 may have prisms elongated along an axis, which maybe oriented parallel or perpendicular to an emission axis 235 of thelight source 204. In some embodiments, the prism axes of the prismaticfilms may be crossed. The front reflector 230 may further include one ormore polarizing films 234, which may include multilayer opticalpolarizing films, diffusely reflecting polarizing films, and the like.The light emitted by the front reflector 230 enters a liquid crystal(LC) panel 280. Numerous examples of backlighting structures and filmsmay be found in, for example, U.S. 2011/0051047.

The following examples are provided to further illustrate the presentinvention and are not intended to limit the invention in any manner.

EXAMPLES Materials Used:

The materials with their sources were as listed in Table 1. Unlessotherwise indicated, all materials were purchased from commercialsources and used as received.

TABLE 1 Materials Designation Description and Sources 2-EHMA2-Ethylhexyl methacrylate, available from Sigma-Aldrich Co., St. Louis,MO 2-EHA 2-Ethylhexyl acrylate, available from Sigma-Aldrich Co., St.Louis, MO C18A 2-Octyl-1-decyl acrylate, Prepared following U.S. Pat.No. 8,137,807 AA Acrylic Acid, available from Sigma-Aldrich Co., St.Louis, MO IOTG Isooctyl thioglycolate, available from Sigma-Aldrich Co.,St. Louis, MO 2-EHTG 2-Ethylhexyl thioglycolate, available from Sigma-Aldrich Co., St. Louis, MO MPA 3-Mercaptopropionic acid, Sigma-AldrichCo., St. Louis, MO DPPS Diphenyl(para-vinylphenyl)phosphine, availablefrom Sigma-Aldrich Co., St. Louis, MO MCR-M07 Monomethacryloxypropylterminated polydimethylsiloxane, available under the trade designation“MCR-M07” from Gelest, Morrisville, PA VAZO 522,2′-Azobis(2,4-dimethylpentanenitrile), available under the tradedesignation “VAZO 52” from E. I. du Pont de Nemours and Co., Wilmington,DE VAZO 88 1,1′-Azobis(cyanocyclohexane), available under the tradedesignation “VAZO 88” from E. I. du Pont de Nemours and Co., Wilmington,DE L101 2,5-Bis(tert-butylperoxy)-2,5-dimethylhexane, available underthe trade designation “LUPEROX 101” from Sigma-Aldrich Co., St. Louis,MO L130 2,5-Dimethyl-2,5-di-(tert-butylperoxy)hexyne-3, available underthe trade designation “LUPERSOL 130” from Pennwalt Corporation, Buffalo,NY CN2003B A modified epoxy acrylate oligomer, available under the tradedesignation “CN2003B” from Sartomer USA, Exton, PA SR833 S Atricyclodecane dimethanol diacrylate, available under the tradedesignation “SR833 S” from Sartomer USA, Exton, PA TPO-L Aphotoinitiator available under the trade designation “LUCIRIN TPO-L”from BASF, MI UV Barrier A 2 mil (~51 micrometer) barrier film availableas “FTB- film M-50” from 3M Co., St. Paul, MN InP/Green/ Quantum dots,obtained as a solution in DDSA/ dodecenyl succinic acid (“DDSA”)/toluenefrom Toluene Nanosys, Milpitas, CA InP/Red/ Quantum dots, obtained as asolution in DDSA/toluene DDSA/ from Nanosys, Milpitas, CA Toluene

Test Methods

A CARY 60 UV-VIS spectrometer was used to measure theultraviolet-visible spectrum of the quantum dot samples.

Quantum Yield Measurements:

Fluorescence cells were from NSG Precision Cells.

Toluene used in the preparation of samples for quantum yieldmeasurements was purchased from Sigma-Aldrich, 244511-1L, Toluene,99.8%.

Quantum dot solutions were prepared in a MBRAUN LABMASTER SP glove boxunder argon atmosphere.

Solutions were prepared in 20 mL glass vials that were dried at least 24hours at 50-60° C. before using in a test. A 5 mL pipette was used todispense the solvent and fill the fluorescence cells, and a woodenapplicator or 100 microliter pipette was used to dispense the quantumdot concentrate solutions.

All containers and equipment to be used in a test were placed in theantechamber of the glove box and pumped on for at least 15 minutesbefore starting the automatic pump/refill cycle used to bring items intothe glove box.

A dilute quantum dot solution in 10 mL toluene was prepared by weighingor pipetting out desired amount of quantum dot concentrates in a 20 mLvial. Then 4 mL of each test solution was pipetted into a separatefluorescence cell. One cell containing toluene only was the blank. Eachcell was sealed with a rubber septa and then all of the cells wereremoved from the glove box to make the quantum yield measurements.

Quantum yield measurements were made on a HAMAMATSU ABSOLUTE PL QUANTUMYIELD SPECTROMETER C11347, available from Hamamatsu Photonics,Hamamatsu, Japan. An excitation wavelength of 440 nm was used for allmeasurements. A built-in program was used to analyze the emissionspectra to calculate the desired spectral quantities, and to correct theemission spectra for self-absorption to give corrected quantum yields.The peak position was determined for the peak maximum in the correctedspectra curve.

Percent Light Transmission (% T)

Percent light transmission (% T) was measured using a BYK HAZEGUARD PLUS(Columbia, Md.). All quantum yields (EQE) were measured by using anabsolute PL QUANTUM YIELD SPECTROMETER C11347 (Hamamatsu Corporation,Middlesex, N.J.).

White Point (Color)

White point (color) was quantified by placing the constructed QDEF filminto a recycling system (FIG. 4) and measuring with a colorimeter(available from Photo Research, Inc., Chatsworth, Calif., under thetrade designation “PR650”). A gain cube with a blue LED light was usedwith the QDEF film, which contained red and green quantum dots, and amicro-replicated brightness enhancement film (available from 3M, St.Paul, Minn., under the trade designation “VIKUITI BEF”). A white pointwas achieved in the recycling system shown in FIG. 4.

Color was quantified by placing the constructed film 310 into arecycling system 300 (FIG. 4) and measuring with a colorimeter 302available from Photo Research, Inc., Chatsworth, Calif., under the tradedesignation PR650. A gain cube 304 with a blue LED light was used withthe film 310, which contained red and green quantum dots, and amicro-replicated brightness enhancement film 308 available from 3M Co.,St. Paul, Minn., under the trade designation VIKUITI BEF. A white pointwas achieved in this recycling system.

An initial white point after film construction was measured andquantified using the CIE1931 (x,y) convention

Molecular Weight Determination

The molecular weight distribution of the compounds was characterizedusing conventional gel permeation chromatography (GPC). The GPCinstrumentation, which was obtained from Waters Corporation, Milford,Mass., included a high pressure liquid chromatography pump (MODEL1515HPLC), an auto-sampler (MODEL 717), a UV detector (MODEL 2487), anda refractive index detector (MODEL 2410). The chromatograph was equippedwith two 5 micrometer PLgel MIXED-D columns available from Varian Inc,Palo Alto, Calif.

Samples of polymeric solutions were prepared by dissolving polymer ordried polymer samples in tetrahydrofuran at a concentration of 0.5percent (weight/volume) and filtering through a 0.2 micronpolytetrafluoroethylene filter that is available from VWR International,West Chester, Pa. The resulting samples were injected into the GPC andeluted at a rate of 1 milliliter per minute through the columnsmaintained at 35° C. The system was calibrated with polystyrenestandards using a linear least squares fit analysis to establish acalibration curve. The weight average molecular weight (“M_(W)”) inDaltons and the polydispersity index (weight average molecular weightdivided by number average molecular weight (“M_(N)”) (i.e.,M_(W)/M_(N))) were calculated for each sample against this standardcalibration curve.

Preparative Example 1 (PE-1): Oligomer/Polymer Composition HavingPendent Phosphine Groups

240 g of 2-EHA, 4.8 grams of DPPS, and 24.5 grams of IOTG were added toa four neck flask equipped with a reflux condenser, thermocouple,mechanical stirrer, and a gas inlet that allows both nitrogen and air tobe bubbled into the solution. The first charge of thermal initiatorsVAZO 52 (0.0125 gram), VAZO 88 (0.0125 gram), and LUPERSOL 101 (0.0125gram) were also added to the flask. The mixture was stirred and heatedto 60° C. under nitrogen bubbling. The temperature of the reactionmixture quickly exothermed and peaked at around 150° C. during thepolymerization before cooling to 80° C. The second charge of VAZO 88(0.0125 gram) dissolved in an additional 5 grams of 2-EHA was added tothe flask. The reaction vessel was heated and held at 150° C. for 90minutes before cooling to 100° C. and purging with air. The reactionproduct was drained and M_(W) was analyzed, giving a value of 6,840Daltons.

TABLE 2* Oligomer Compositions with DPPS Component PE-1 PE-2 PE-3 2-EHA89.1 87.2 — C18A — — 87.2 DPPS 1.8 4.6 4.6 IOTG 9.1 8.2 8.2 VAZO 520.005 0.005 0.005 VAZO 88 0.010 0.010 0.010 L101 0.010 0.010 0.010 M_(W)6,840 12,500 6,650 *amounts of components are parts by weight; M_(W)values are in Daltons

Preparative Examples 2 and 3 (PE-2 and PE-3)

Additional oligomer/polymer compositions having pendent phosphine groupswere generated, using this same method as in PE-1, except usingmaterials in the amounts as indicated in Table 2. In the case of PE-3,C18A was used in place of 2-EHA. The resulting M_(W) values were aslisted in Table 2.

Preparative Examples 4 to 10 (PE-4 to PE-10)

Additional oligomer/polymer compositions having pendent phosphine groupswere generated, using this same method as in PE-1, except usingmaterials in the amounts as indicated in Table 3. In the case of PE-9,C18A was used in place of 2-EHA; and in the case of PE-10, 2-EHMA wasused in place of 2-EHA. In all cases, the MCR-M07 component (amonomethacryloxypropyl-terminated polydimethylsiloxane) was added incombination with the initial charge of (meth)acrylate component, DPPS,and thioglycolate component. The resulting M_(W) values were as listedin Table 3.

TABLE 3* Oligomer/polymer Compositions with PDMS silicone Component PE-4PE-5 PE-6 PE-7 PE-8 PE-9 PE-10 2-EHA 45 63 47.5 47 46 — — 2-EHMA — — — —— — 47 C18A — — — — — 47 — MCR-M07 45 31 47.5 47 46 47 47 DPPS 2 2 2 4 42 2 IOTG 8 — — — — — — 2-EHTG — 4 3 2 4 4 4 VAZO 52 0.005 0.005 0.0050.005 0.005 0.005 0.005 VAZO 88 0.010 0.010 0.010 0.010 0.010 0.0100.010 L101 0.010 0.010 0.010 0.010 0.010 0.010 0.010 M_(W) 9,460 16,10016,100 107,200 29,850 5,360 5,960 *amounts of components are parts byweight; M_(W) values are in Daltons

Preparative Example 11 (PE-11): Oligomer/Polymer without PendantPhosphine Groups

207 grams of 2-EHA, 105 grams of C18A, 21.75 grams of AA, and 18.55grams of MPA were added to a four neck flask equipped with a refluxcondenser, thermocouple, mechanical stirrer, and a gas inlet that allowsboth nitrogen and air to be bubbled into the solution. The first chargeof thermal initiators VAZO 52 (0.018 gram), VAZO 88 (0.018 gram), andLUPERSOL 130 (0.0126 gram) were also added to the flask. The mixture wasstirred and heated to 60° C. under nitrogen bubbling. The temperature ofthe reaction mixture quickly exothermed and peaked at around 150° C.during the polymerization before cooling to 80° C. The second charge ofVAZO 88 (0.018 gram) and LUPERSOL 130 (0.007 gram) dissolved in anadditional 5 grams of 2-EHA was added to the flask. The reaction vesselwas heated and held at 150° C. for 90 minutes before cooling to 100° C.and purging with air. The reaction product was drained and M_(W) wasmeasured, giving a value of 4,930 Daltons.

Example 1 (EX-1): Preparation of an InP Dot Concentrate with PE-6

To a 250 mL Schlenk flask equipped with a stir bar was added 10.04 gramsof PE-6. The joint of the flask was greased and the oligomer wasdegassed under vacuum. The flask was then disconnected from the Schlenkline and taken inside an MBRAUN LABMASTER SP glove box. The vacuuminside the flask was released under argon-atmosphere inside the glovebox. To the flask was added 36.0 grams of InP/Green/DDSA/Toluenesolution (Lot no. 374-29C) and 9.0 grams of InP/Red/DDSA/Toluenesolution (Lot no. 374-29D). The flask was sealed properly inside theglove box, and then taken out from the glove box. The flask wasre-introduced to the Schlenk line and toluene was evaporated under highvacuum. After the removal of toluene, the flask was disconnected fromSchlenk line and taken inside the glove box again. An amount of 9.9grams of dot concentrate was obtained after transferring the dotconcentrate to a pre-weighed glass jar. The final optical density of thedot concentrate with PE-6 was approximately 45, with a green InP: redInP dot ratio of about 4:1. The quantum yield and photophysicalparameters were measured and were as summarized in Table 4. Quantumyield and photophysical parameters for the InP/Green/DDSA/Toluene andInP/Red/DDSA/Toluene were also measured, with results as summarized inTable 4.

TABLE 4 Quantum yield and photophysical properties of dot concentratesQuantum Peak Wavelength Sample yield (nm) FWHM (nm) EX-1 dotconcentrate, 0.81 531 (green); 615 41 (green); 50 18.4 mg (red) (red) 50microliters of 0.84 530 40 InP/Green/DDSA/ Toluene 50 microliters of0.76 616 45 InP/Red/DDSA/Toluene FWHM = Full width half maximum

Preparative Example 12 (PE-12): Preparation of an Acrylate Matrix forQDEF

All materials as shown in Table 5 were weighed out in the dark into adark glass jar fitted with a lid. The solution was mixed usingmechanical stirrer for 10 minutes at 1000 rpm. The jar was then heatedat 65° C. for 10 minutes followed by vacuum evaporation for 15 minutesin a vacuum oven. The jar was taken out of the vacuum oven, stirredusing a wooden applicator, heated for 10 minutes at 65° C., and thenreintroduced into the vacuum oven. This process was continued one moretime to reduce bubbling/frothing of the resin, which was used as suchfor preparation of QDEF.

TABLE 5 Acrylate matrix compositions Amount, Weight Material gramspercent CN2003B 100.04 49.62 SR833 S 100.12 49.66 TPO-L 1.45 0.72

Example 2 (EX-2): Preparation of a QDEF

The formulation preparation, coating, and curing was carried out insidea glove box. 1.839 grams of dot-polymer concentrate EX-1 was added to18.45 grams of acrylate matrix formulation PE-12 in a white dac mixercup inside the glove box. The mixture was stirred using a mechanicalstirrer at 1000-1100 rpm for 1-2 minutes. The mixture was then coated inbetween 2 mil (˜51 micrometer) barrier films at a thickness of 100micrometers, using a knife coater. The coating was then cured using aCLEARSTONE CF2000 UV LED at 385 nm for 60 seconds at 100% power.

Comparative Example 1 (CE-1): Preparation of a Comparative QDEF

The formulation preparation, coating, and curing was carried out insidea VAC-Atmosphere glove box. 2.337 grams of green InP/DDSA (Lot no.354-9-7A, 354-9-7B, 354-9-9C) in PE-11 and 0.74 gram red InP/DDSA(354-9-10A, 354-9-10E, 354-9-10F) in PE-11 were added to 20.44 grams ofthe matrix formulation of PE-12 in a white dac mixer cup inside theglove box. The mixture was stirred using a mechanical stirrer at1000-1100 rpm for 1-2 minutes. The mixture was then coated in between 2mil (˜51 micrometer) barrier films at a thickness of 100 micrometersusing a knife coater. The coating was cured using a CLEARSTONE CF2000 UVLED at 385 nm for 60 seconds at 100% power.

Measurements of the QDEF of EX-2 and CE-1 were obtained. Twomicro-replicated brightness enhancement films (available from 3M, St.Paul, Minn., under the trade designation “3M BEF”) were placed in a 90degree crossed configuration above the QDEF. A white point and luminancevalue was measured for each film sample in this recycling system.Measurements were carried out in a black enclosure to eliminate straylight sources. External quantum efficiency (EQE) was measured usingabsolute PL QUANTUM YIELD SPECTROMETER C11347 (Hamamatsu Corporation,Middlesex, N.J.). All data were the average of two measurements. Theresults were as summarized in Tables 6 and 7.

TABLE 6 EQE and optical measurements of QDEF % Sample Transmission HazeLuminance EQE (%) EX-2 79.35 91.7 316.1 74.2 CE-1 81.5 72.5 286.9 64.3

TABLE 7 Color and white point measurements of QDEF Sample x y %Efficiency PWL-G PWL-R FWHM-G FWHM-R EX-2 0.2767 0.2589 46.5 542 nm 622nm   43 nm 50.3 nm CE-1 0.2662 0.2453 41.0 541 nm 619 nm 41.7 nm 54.3 nmX = color in the red dimension; y = color in the green dimension; PWL-G= Peak wavelength for green light emission; PWL-R = Peak wavelength forred light emission; FWHM-G = Full width half maximum for green lightemission; FWFHM-R = Full width half maximum for red light emission.

1. A composite particle comprising a fluorescent core/shell nanoparticleand a stabilizing carrier fluid comprising a (meth)acrylate copolymerhaving pendent arsine, stibine or phosphine groups.
 2. The compositeparticle of claim 1 wherein the pendent groups are of the formula:

wherein each R¹ is a hydrocarbyl group including alkyl, aryl, alkaryland aralkyl; R² is a divalent hydrocarbyl group selected from alkylene,arylene, alkarylene and aralkylene; Z is P, As or Sb; Q is a functionalgroup selected from —CO₂—, —CONR³—, —NH—CO—NR³—, and —NR³—, where R³ isH or C₁-C₄ alkyl, and subscript x is 0 or
 1. 3. The composite particleof claim 1 wherein the copolymer is of the formula:˜[M^(ester)]_(a)-[M^(stab)]_(b)-[M^(sil)]_(c)-[M^(acid)]_(d)-[M^(other)]_(e)˜,where [M^(ester)] represents (meth)acrylate ester monomer units havingsubscript a parts by weight; [M^(stab)] represents monomer units havingpendent phosphine, arsine or stibine groups and subscript b parts byweight; [M^(sil)] represents silyl-functional monomer units havingsubscript c parts by weight; [M^(acid)] represents acid-functionalmonomer units having subscript d parts by weight; and [M^(other)]represents other monomer units having subscript e parts by weight. 4.The composite particle of claim 3 wherein subscript a of [M^(ester)] is20-90 parts by weight; subscript b of [M^(stab)] is 1 to 10 parts byweight, subscript c of [M^(sil)] is 0 to 70 parts by weight, subscript dof [M^(acid)] is 0 to 15 parts by weight, and subscript e of [M^(other)]is 0 to 5 parts by weight.
 5. The composite particle of claim 3 whereinsubscript c of [M^(sil)] is 1 to 50 parts by weight.
 6. The copolymer ofclaim 1 wherein the copolymer is derived from monomers of the formula:

wherein wherein each R¹ is a hydrocarbyl group including alkyl, aryl,alkaryl and aralkyl; R² is a divalent hydrocarbyl group selected fromalkylene, arylene, alkarylene and aralkylene; Z is P, As or Sb; Q is afunctional group selected from —CO2-, —CONR³—, —NH—CO—NR³—, and —NR³—,and each R³ is independently H or C₁-C₄ alkyl, and subscript x is 0or
 1. 7. The composite particle of claim 1 wherein at least one of saidR¹ groups is an aryl or alkaryl group.
 8. The composite particle ofclaim 1 wherein two of said R¹ groups are an aryl or alkaryl group. 9.(canceled)
 10. (canceled)
 11. The composite particle of claim 1 furthercomprising a surface modifying ligand bound to the surface of thenanoparticle of the formula:R⁵—R²(X)_(n) wherein R⁵ is (hetero)hydrocarbyl group having C₂ to C₃₀carbon atoms; R² is a hydrocarbyl group including alkylene, arylene,alkarylene and aralkylene; n is at least one; X is a ligand group. 12.The composite particle of claim 1 wherein the pendent groups are of theformula:

wherein each R¹ is a hydrocarbyl group including alkyl, aryl, alkaryland aralkyl; R² is a divalent hydrocarbyl group selected from alkylene,arylene, alkarylene and aralkylene; Z is P, As or Sb; Q is a functionalgroup selected from —CO₂—, —CONR³—, —NH—CO—NR³—, and —NR³—, where R³ isH or C₁-C₄ alkyl, and subscript x is 0 or 1, and R⁶ is a divalenthydrocarbyl group selected from alkylene, arylene, alkarylene andaralkylene.
 13. The composite particle of claim 1 wherein the corecomprises InP, CdS or CdSe. 14-17. (canceled)
 18. The composite particlecomprising: a fluorescent semiconductor core/shell nanoparticlecomprising: an InP core; an inner shell overcoating the core, whereinthe inner shell comprises zinc selenide and zinc sulfide; and an outershell overcoating the inner shell, wherein the outer shell compriseszinc sulfide; and the stabilizing carrier fluid of claim
 1. 19. Acomposition comprising the composite particle of claim 1 furthercomprising a secondary carrier fluid.
 20. A composition comprising thecomposite particle of claim 1 dispersed in droplets of the stabilizingcarrier fluid, said droplets dispersed in a polymeric binder.
 21. Thecomposition of claim 19 wherein the polymeric binder comprisespolysiloxanes, fluoroelastomers, polyamides, polyimides,polycaprolactones, polycaprolactams, polyurethanes, polyvinyl alcohols,polyvinyl chlorides, polyvinyl acetates, polyesters, polycarbonates,polyacrylates, polymethacrylates, polyacrylamides, epoxy resins andpolymethacrylamides
 22. An article comprising the composite particle ofclaim 1 dispersed in the cured polymeric binder between two barrierfilms. 23-25. (canceled)
 26. The composite particles of claim 1 furthercomprising a secondary stabilizing additives of the formula:

wherein R¹ is a hydrocarbyl group, including aryl, alkaryl, alkyl oraralkyl, R² is R¹ when a is one and a C₁-C₁₀ divalent alkylene when a is2; Z is P, As or Sb.
 27. The composite particle of claim 1 wherein theweight average molecular weight (M_(w)) of the copolymer is generally1000-200,000.
 28. Copolymers of the formula:˜[M^(ester)]_(a)-[M^(stab)]_(b)-[M^(sil)]_(c)-[M^(acid)]_(d)-[M^(other)]_(e)˜,where where [M^(ester)] represents (meth)acrylate ester monomer unitshaving subscript a parts by weight; [M^(stab)] represents monomer unitshaving pendent phosphine, arsine or stibine groups and subscript b partsby weight; [M^(sil)] represents silyl-functional monomer units havingsubscript c parts by weight; [M^(acid)] represents acid-functionalmonomer units having subscript d parts by weight; and [M^(other)]represents other monomer units having subscript e parts by weight;wherein subscript a of [M^(ester)] is 20-90 parts by weight; subscript bof [M^(stab)] is 1 to 10 parts by weight, subscript c of [M^(sil)] is 0to 70 parts by weight, subscript d of [M^(acid)] is 0 to 15 parts byweight, and subscript e of [M^(other)] is 0 to 5 parts by weight. 29.The copolymer of claim 28 wherein the pendent groups of [M^(stab)] areof the formula:

wherein each R¹ is a hydrocarbyl group including alkyl, aryl, alkaryland aralkyl; R² is a divalent hydrocarbyl group selected from alkylene,arylene, alkarylene and aralkylene; Z is P, As or Sb; Q is a functionalgroup selected from —CO₂—, —CONR³—, —NH—CO—NR³—, and —NR³—, where R³ isH or C₁-C₄ alkyl, and subscript x is 0 or 1, and R⁶ is a divalenthydrocarbyl group selected from alkylene, arylene, alkarylene andaralkylene.